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Dr Gregory Heness

Biography

After completing a B.App.Sc. (Hons) in Engineering Materials Science, Greg worked on his Masters degree investigating phosphate bonded alumina biocomposites. During this time Greg was responsible for the ceramics laboratories at NSWIT and then UTS as well as the thermal analysis facility. From 1988 to 1998 Greg carried out part-time lecturing at UTS as well as part-time teaching at TAFE, all in the area of materials science. In 1998, he was appointed as a lecturer in the Department of Materials Science, having enrolled in his PhD at the University of Sydney. The topic of the thesis was “Fracture and Fatigue of Particulate MMCs”, working closely with Comalco Australia. On completion on 1996, Greg enrolled in the Graduate Certificate in Higher Education.

In the last five years Greg has been involved in research teams both inside UTS and in collaboration with other universities that has resulted in successful competitive grant applications of more that $1.5 million. This has resulted in the development of a network of sophisticated materials testing and characterisation equipment. Since 1990 the total of successful competitive grants is nearly $2.5million.
Greg is currently the Treasurer of the Australian Fracture Group and serves on the Editorial Board of The Australasian Ceramics Society’s journal and is a reviewer for The Institute of Materials Engineering, Australia’s Materials Forum.

Professional

NSW State President, Institute of Engineering Materials Australia

Federal Councillor, Institute of Engineering Materials Asutralia

Treasurer, Australian Fracture

Image of Gregory Heness
Visiting Fellow, School of Mathematical and Physical Sciences
BAppSc (NSWIT), Graduate Certificate in Higher Education (UTS), MAppSc (UTS), PhD (Syd)
 

Research Interests

Current research interests include

  • nanoscaled metal matrix composites,
  • mechanical properties of nanoscaled ceramic coatings on metal substrates
  • nano-particle reinforced polymer composites
  • Use of natural fibres for cheap building materials
  • Nano-composite-timber hybrids
  • Electrical and magnetic polymer nanocomposites
  • Mechanical properties of porous ceramics

Greg is also active in consulting in failure analysis, mechanical testing and materials characterisation

Chapters

Choi, A., Ben-Nissan, B. & Heness, G.L. 2014, 'Using finite element analysis (FEA) to understand the mechanical properties of ceramic matrix composites' in Low, J. (ed), Advances in Ceramic Matrix Composites, Woodhead, Cambridge, pp. 286-311.
Cortie, M.B., Stokes, N.L., Heness, G.L. & Smith, G. 2014, 'Applications of Nanotechnology in the Building Industry' in David Rickerby (ed), Nanotechnology for Sustainable Manufacturing, CRC Press, USA.
Choi, A.H., Matinlinna, J.P., Heness, G. & Ben-Nissan, B. 2014, 'Nanocomposites for Biomedical and Dental Applications' in Handbook of Functional Nanomaterials. Volume 4 - Properties and Commercialization, Nova Publishing, New York, pp. 149-173.
During the last decade, there has been a major increase in the interest of nanostructured materials in advanced technologies such as biomedical and dental technology. Nanostructured materials are associated with a variety of uses within the biomedical field, for example, nanoparticles in drug-delivery system, in biomaterial science and diagnostic systems and in regenerative medicine. By definition, a biomaterial is a nondrug substance that is ideal for inclusion in systems that replace or extend the function of bodily tissues or organs. The key factors in the clinical success of any biomaterial are its biocompatibility and biofunctionality, both of which are related directly to tissue/implant interface interactions. Nanocomposites can be described as a heterogeneous combination of two or more materials, in which at least one of those materials should be on a nanometer-scale. By using the composite approach, it is possible to manipulate the mechanical properties such as strength and modulus of the composites closer to those of natural bone, with the help of secondary substitution phases. Currently, the most common composite materials used for clinical applications are those selected from a handful of available and well-characterized biocompatible ceramics and the combination with metals and polymers as composites and hybrids. This approach is currently being explored in the development of a new generation of nanocomposites with a widened range of biomedical and dental applications. The aim of this chapter is to provide information relating to the use of nanocomposites for biomedical and dental applications.
Heness, G.L. 2012, 'Metal-polymer Nanocomposites' in Fengge Gao (ed), Advances in Polymer Nanocomposites, Woodhead, UK, pp. 164-177.
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Polymers- general properties are low strength and stiffness, poor conductors of electricity and heat, high dielectric strength, poor thermal properties and are nonmagnetic. Attempts over the years, have been made to change and/or improve some of these to increase the availability of polymers to a new range of applications. Recently, the use of nanoparticles has been shown great interest by researchers. This chapter looks at metal nanoparticles which exhibit uniquely different electronic and optical properties to their bulk counterparts. It is these interesting new properties that are one of the major driving forces for incorporation into polymer matrices. I particular methods of incorporation of the metal nanoparticles into the polymer, resultant properties, applications and future trends will be discussed

Conferences

Heness, G.L. 2013, 'Metal Nanoparticle Reinforced Polymer Composites Processing', International Conference on Materials and Processing Technology, International Conference on Materials and Processing Technology, King Mongkut's University of Technology, Thonburi Thailand, Bangkok, Thailand, pp. 188-193.
There is a desire amongst the materials community to alter the properties of polymers to increase their usefulness. Besides altering the polymer chemistry the addition of inorganic particles and fibres has been undertaken for many decades. Nanoparticles have shown much promise due to their inherently different properties to their bulk counterparts. This paper deals with, in particular, metal nanoparticles. Their electrical optical, thermal and magnetic properties are a function of particle size and, thus, the properties are tunable, creating a range of properties that can be "dialed up". A review of techniques for incorporation into the polymer matrix will be discussed and novel examples given.
Heness, G.L. 2013, 'Circumferential notch tension testing of 7A04 metal matrix composites', Proc. 8th International Conference on Structural Integrity & Fracture, International Conference on Structural Integrity & Fracture, RMIT University, Melbourne, Australia, pp. 85-88.
The standard test method for determining plane-strain fracture toughness, KIC, in mode I often require a large specimen size and plenty of available material when performing continuous monitoring of operating components in power plants. Circumferential notch tension (CNT) testing can be considered as an alternative fracture toughness test when there only small amounts of available materials or when bulk specimen sizes were unsatisfactory for standard test requirements. In this study, CNT was applied to determine the fracture toughness of a series of particulate reinforced 7A04 metal matrix composites (MMC) reinforced with 7.5 vol. % and 10 vol. % SiC particulates. A comparison test on the 7A04 base alloy was also performed. All materials were fabricated using stir-cast processing and then extruded into bars. Preliminary results found that the base alloy exhibited higher fracture toughness when compared to the MMC counterpart since it was generally understood that increasing the reinforcement will lead to lower fracture toughness values. Furthermore, although increasing the particulate reinforcement serves to increase the overall strength of the material it was the constraint imparted by the reinforcement that led to lower fracture toughness values.
Heness, G.L. 2010, 'Small Punch Test of LC4/SiCp Metal Matrix Composites', Advanced Materials Research, Trans Tech Publications, Jeonju, Korea, pp. 439-442.
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Mak, J.C., Wuhrer, R., Heness, G.L., Yeung, W.Y., Callaghan, M., Wei, T., Qin, J., Lu, W. & Zhang, D. 2008, 'Small punch test of advanced in-situ synthesized Ti metal matrix composites', International Conference on Multi-Functional Materials And Structures - Advanced Materials Research, International Conference on Multi-Functional Materials And Structures, Trans Tech Pubications, Hong Kong, pp. 738-741.
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Particulate reinforced 10 vol.% (TiB+TiC)/Ti-6Al-4V metal matrix composites (MMCs) were produced by in-situ synthesis using vacuum arc re-melting process, and the mechanical properties of the metal matrix composites were assessed by the small punch testing (SPT). Mechanical properties of the in-situ synthesized Ti MMCs were studied and compared with the Ti base alloy. From the test data, the fracture properties and equivalent fracture strain of the test materials were characterised. The fracture mechanism of the test samples was examined using scanning electron microscopy.
Bandyopadhyay, S., Luechinger, N.A., Heness, G., Booth, N., Grass, R.N. & Stark, W.J. 2008, 'Metal/polymer nanocomposites as potential opto - Magneto - Electronic materials', 8th World Congress: Enabling Technologies and New Markets, Nanocomposites 2008.
Heness, G.L. & Ben-Nissan, B. 2006, 'Porous phosphate bonded alumina strengthened and toughened with limited additions of second phase particles', International Conference and Exhibition on Strurctural Integrity and Failure, Structural Integrity and Failure, Australia Fracture Group & Institute of Materials Engineering Australasia, Sydney, pp. 324-330.
Flexural strength, diametral strength, fracture toughness and fracture surface energy of phosphate, bonded alumina composites were all found to increase with a limited addition of either silicon nitirde of partially stabilised zirconia particles. the addition of monoclinic zirconia and glass spheres showed little improvement of the above properties. These increases in strength are explained using crack bowing theory.
Heness, G.L., Tam, W. & Bandyopadyay, S. 2006, 'Flexural and impact properties of binary reinforced epoxy nanocomposites', ACUN-5 International Composites Conference, ACUN-5 International Composite Conference: Development in Composites: Advacned infrastructural, Natural & Nano-Composites, UNSW, UNSW, pp. 352-358.
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A binary system of nano-reinforcement was used to increase flexural strength, flexural modules and impact strength of bisphenol-A type epoxy resin. Montmorillonite and alumina particles aere used as midifiers. Each modifier, by itself, was found to increase these properties and further the use of both was found to have a synergistic effect.
Zhu, P., Yeung, W.Y., Heness, G.L. & Duggan, B.J. 2005, 'On thermomechanical processing of high ductility SiCp/Zn-22wt.%Al metal matrix composites', Materials Science Forum, Pacific Rim International Conference on Advanced Materials and Processing, Trans Tech Publications Ltd, Beijing, China, pp. 979-984.
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SiCp/Zn-22 wt% Al metal matrix composites of different particulate sizes have been prepared and tensile tested at 250 degrees C at various strain rates. Scheduled thermomechanical treatment of structural refinement was employed to enhance the ductility o
Heness, G.L. & Mai, Y. 2001, 'The Fracture Toughness of Some Metal Matrix Composites - Comparison of Techniques', Proceedings of Advances in Fracture Research, Advances in Fracture Research, Elsevier Science, Honolulu, pp. 0-0.
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Heness, G.L. 1984, 'INVESTIGATION OF ALUMINA PHOPHATE BIOCERAMIC COMPOSITE.', Proceedings - Australian Ceramic Conference, pp. 275-281.
A completely new area of ceramic application involves the use of ceramics as surgical implants within a living body and is given the term bioceramics. Many implants, such as artificial hip joints, must remain in the body for the life of the patient. For this reason the search for a suitable material has come to the field of ceramics. No material placed in the human body can be considered completely inert. However, by their very nature, ceramics do not suffer from corrosion as do metals.

Journal articles

Heness, G.L. 2014, 'Comparative Study of Conversion of Coral with Ammonium Dihydrogen Phosphate and Orthophosphoric Acid to Produce Calcium Phosphates', Journal of the Australian Ceramic Society, vol. 50, no. 2, pp. 154-161.
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Biogenic materials like corals, which are readily available, could be used to produce bioceramic materials and address significant advantages due to their unique structures and chemical compositions that contain Mg and Sr. Many conversion processes has been in the past proposed. In this work, a comparison study between the conversion of coral with orthophosphoric acid and ammonium dihydrogen phosphate was conducted. The resultant structures and compositions were studied using XRD, ICP-MS, SEM and FTIR. The results show that with phosphoric acid the coral was converted into mainly monetite (92%). The ammonium dihydrogen phosphate converted approximately 76% of the coral to hydroxyapatite through solid state reactions. The two routes proved to be effective in producing bioceramic materials from corals under moderate conditions of temperature with a basic condition favouring the yield of hydroxyapatite.
Heness, G.L., Booth, N. & Ben-Nissan, B. 2014, 'Specimen Size Effects on the Compressive Strength of Porous, Open Cell Ceramics - Size Matters', Journal of the Australian Ceramics Society, vol. 50, no. 2, pp. 176-179.
Mak, J.C., Wei, T., Wuhrer, R., Yeung, W.Y., Heness, G.L. & Zhang, D. 2013, 'A Solution for Estimating the Tensile Yield Strength From Small Specimens', Journal of Testing and Evaluation, vol. 41, no. 4, pp. 647-650.
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The small punch test is an innovative test that utilises small disc-shaped specimens to assess the mechanical behaviour of materials. The main advantage is the relatively small specimen size. In this article, a modified analytical solution for the small
Samapisut, S., Heness, G.L., Tipparach, U. & McCredie, G. 2012, 'Effects of Magnetron Discharge Power and N2 Flow Rate for Preparation of TiCrN Thin Film', Procedia Engineering, vol. 32, pp. 1135-1138.
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Titanium Chromium Nitride (TiCrN) multilayer coatings on cutting tools, press molds and dies can be used to prolong their life cycle because of their superior corrosion and oxidation resistance. We investigated on three effecting conditions, the magnetron discharging powers of Ti and Cr targets and N2 flow rate. TiCrN multilayer coatings were prepared by dual DC magnetron sputtering. The crystallography and microstructure of the films were investigated by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystalline structures were obtained the cubic and mixed phases of Ti0.5Cr0.5N with the mean lattice parameters of a = b = c = 4.238 Å and TiCrN2 with the mean lattice parameters of a = b = c = 4.1835 Å for the condition of discharging powers on Ti and Cr target, respectively. However, the N2 flow rate condition, the orthorhombic oriented structure occurred with the mean lattice parameters of a = 2.962 Å, b = 4.130 Å and c = 2.875 Å. The morphology of TiCrN thin films show the average grain size ~ 100200 nm, and the thickness of ~1 micron Cr-layer, ~0.5 micron CrN-layer and ~2 micron TiCrN-layer.
Jiang, L., Fan, G., Li, Z., Chen, Z., Zhang, D., Kai, X., Humphries, S.R., Heness, G.L. & Yeung, W.Y. 2011, 'An approach to the uniform dispersion of a high volume fraction of carbon nanotubes in aluminum powder', Carbon, vol. 49, no. 6, pp. 1965-1971.
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A slurry based process was developed to achieve the uniform dispersion of a high volume fraction of carbon nanotubes (CNTs) in aluminum powder. Al powder was subjected to surface modification to introduce a hydrophilic polyvinyl alcohol (PVA) membrane on its surface, which has good wettability and strong hydrogen bonding interactivity with functionalized CNTs. It was found that, when mixed with a CNT aqueous suspension, the PVA-modified Al (Al@PVA) powder resulted in much better adsorption uniformity of CNTs than the untreated Al powder. The adsorption capacity of CNTs was greatly enhanced by using nanoflake Al powder, which has better geometric compatibility with the CNTs and a larger surface area than spherical powder. Consequently, a uniform dispersion of 20 vol.% CNTs was achieved in the nanoflake Al@PVA powders. The advantage of this approach is that it provides easy control over adsorption uniformity and capacity of CNTs in a metal matrix, through the combination of surface modification and thickness adjustment of the metal flake powders.
Roest, R.S., Latella, B.A., Heness, G.L. & Ben-Nissan, B. 2011, 'Adhesion of sol-gel derived hydroxyapatite nanocoatings on anodised pure titanium and titanium (Ti6Al4V) alloy substrates', Surface & Coatings Technology, vol. 205, no. 11, pp. 3520-3529.
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The mechanical properties and adhesion behaviour of sol-gel derived hydroxyapatite (HA) nanocoatings on commercially pure (cp) titanium (Ti) and Ti6Al4V alloy have been determined and related to anodising treatment. The surface roughness, wetting and coating characteristics were examined using profilometry, contact angle, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Nano-indentation was used to determine the Young's modulus and hardness of the coatings, while microtensile tests were used to introduce controlled strains in the coatings through the cp Ti and TiAl6V4 alloy substrates, from which the strength, fracture toughness and adhesion behaviour could be ascertained based on multiple cracking and delamination events. The toughness of the HA coatings is found to be slightly lower to that of equivalent bulk pure HA ceramics. The substrate and the anodized layer thickness have the most influence on the interfacial adhesion of HA, with nanocoatings on Ti6Al4V exhibiting superior interfacial bonding in comparison to cp Ti.
Chaysuwan, D., Sirinukunwattana, K., Kanchanatawewat, K., Heness, G.L. & Yamashita, K. 2011, 'Machinable glass-ceramics forming as a restorative dental material', Dental Materials Journal, vol. 30, no. 3, pp. 358-367.
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MgO, SiO(2), Al(2)O(3), MgF(2), CaF(2), CaCO(3), SrCO(3), and P(2)O(5) were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhar
Mak, J.C., Wuhrer, R., Heness, G.L., Qin, J., Lu, W., Zhang, D. & Yeung, W.Y. 2008, 'Microstructural Analysis on Ti-6Al-4V and10 Vol.% (TiB+TiC)/Ti-6Al-4V Metal Matrix Composites', Advanced Materials Research, vol. 32, no. 1, pp. 115-118.
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Particulate reinforced Ti based metal matrix composites (MMCs) were made by in-situ synthesis using vacuum arc re-melting process. The microstructure of the Ti-6Al-4V base alloy and 10 vol.% (TiB+TiC)/Ti-6Al-4V metal matrix composites was examined. The particulate reinforcements were analysed and identified TiB and TiC particles. The particle distribution was analysed using the quadrat method over 1620 quadrats. A homogeneous particle distribution was found to establish in the composites. The experimental distribution of the reinforcements agreed well with the theoretical Poisson distribution. A skew factor, which characterizes the degree of asymmetry of a statistical distribution, of 1.108 was determined for the particle distribution in the material.
Heness, G.L., Yeung, W.Y. & Wuhrer, R. 2008, 'Interfacial strength development of roll-bonded aluminium/copper metal laminates', Materials Science & Engineering A, vol. 483-484, pp. 740-742.
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The development of the phases in the interface of roll-bonded Al/Cu metal laminates controls the strength. Phase development as a function of sintering time was monitored via X-ray diffraction and X-ray mapping. Both techniques revealed essentially the same phase presence and highlighted a limitation of X-ray diffraction. Initial rolling reduction has no effect on phase development but does affect the interface thickness.
Luechinger, N.A., Booth, N.G., Heness, G.L., Bandyopadyay, S., Grass, R.N. & Stark, W.J. 2008, 'Surfactant-free, melt-processable metal-polymer hybrid materials: Use of graphene as a dispersing agent', Advanced Materials, vol. 20, no. 16, pp. 3044-3049.
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Graphene coatings on metal nanoparticles work as lubricants and dispersing agents and can fully replace Currently used surfactants. These high-temperature-stable metal-polymer hybrid materials can be shaped by injection molding, enabling rapid manufactur
Heness, G.L., Booth, N.G. & Ben-Nissan, B. 2008, 'Does size matter? the effect of volume on the compressive strength of open cell brittle ceramics', Advanced Materials Research, vol. 41-42, pp. 221-226.
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This study investigates the effect of specimen volume o the compressive strenmgth of open cell brittle ceramics. A siries of unconfined compression tests were carried out on specimens ranging in volume. The crushing strength and apparent stiffness were measured and these results are correlated with the volume of material stressed. It was found that as the volume of material tested decreased the strength decreased.
Mak, J.C., Wuhrer, R., Booth, N.G., Fanos, P., Heness, G.L. & Yeung, W.Y. 2007, 'Equal channel angular extrusion of zinc-aluminium metal matrix composites', Key Engineering Materials, vol. 345-346, no. 1, pp. 113-116.
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Equal channel angular extrusion (ECAE) was employed in an attempt to develop nanostructural metal matrix composites with homogenized distribution of reinforcing particles. Zn-Al metal matrix composites reinforced with 5 ?m SiC particulates were produced by casting method. A non-uniform distribution of the reinforcing particles was evident in the metal matrix. With repetitive shear deformation imposed via the ECAE process, substantial structural improvement was achieved and the reinforcing particulates were de-clustered into a finely dispersed distribution throughout the metal matrix. The homogeneity of the particle distribution was studied by the Quadrat method and the skew factors were determined. It was found that the skew factors were substantially reduced after 8 extrusion passes, showing the homogeneity of the particle distribution was greatly improved in the composites.
Heness, G.L., Stevens, M.G. & Dossett, B. 2007, 'The Effect Of Surface Treatment On Delamination For A Nylon Interleaving Material', Materials forum, vol. 31, pp. 90-95.
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One method of controlling delamination and increasing the inter-lamina toughness in composite laminates is the use of thermoplastic interleaving films, primarily to absorb energy. In this study the effect of controlling the surface energy of a nylon interleaving film on the interlaminar fracture toughness was investigated. It was found that as the surface energy of the nylon increased so did the Mode I delamination resistance. Surface energy was measured via dynamic contact angle measurements and delamination resistance via double cantilever beam specimens. It was concluded that control of the surface energy of the interleaving material is paramount in controlling delamination.
Heness, G.L. 2007, 'THE EFFECT OF SURFACE TREATMENT ON DELAMINATION FOR A NYLON INTERLEAVING MATERIAL', Materials Forum, vol. 31, pp. 90-95.
Roest, R.S., Heness, G.L., Latella, B.A. & Ben-Nissan, B. 2006, 'Fracture toughness of nanoscale hydroxapatite coatings on titanium substrates', Key Engineering Materials, vol. 306-308, no. 1, pp. 1307-1312.
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In the biomedical field, the surface modification of titanium aims to inhibit wear, reduce corrosion and ion release, and promote biocompatibility. Sol-gel-derived ceramic nanoscale coatings show promise due to their relative ease of production, ability
Mansell, M.W., Heness, G.L. & Yeung, W.Y. 2005, 'X-ray photoelectron spectroscopy analysis of oxide formation of 8150 aluminium foils', Materials Forum, vol. 29, pp. 579-583.
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It is known that an enrichment of metallic elements in the oxide layer of aluminium foils may significantly affect their surface properties. Elemental compositions at various depths of the newly developed 8150 aluminium foil were determined by x-ray photoelectron spectroscopy for selected heat treatment conditions.
Heness, G.L. & Ben-Nissan, B. 2004, 'Innovative bioceramics', Materials Forum, vol. 27, pp. 104-114.
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Overall, the benefits of advanced ceramic materials in biomedical applications have been universally appreciated, specifically, in terms of their strength, biocompatibility and wear resistance. However, the amount of supporting data is not large and the continuous development of new methods is pertinent for better understanding of the microstructure properties relationshp and in general, for obtaining new directives for thier further improvement. This paper gives an overview of some of the more innovative applications of bioceramics in medicine.
Heness, G.L. & Ben-Nissan, B. 2004, 'Innovative Bioceramics', Materials Forum, vol. 27, no. 2004, pp. 104-114.
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Overall, the benefits of advanced ceramic materials in biomedical applications have been universally appreciated, specifically, in terms of their strength, biocompatibility and wear resistance. However, the amount of supporting data is not large and the continuous development of new methods is pertinent for better understanding of the microstructureproperties relationship and, in general, for obtaining new directives for their further improvement. This paper gives an overview of some of the more innovative applications of bioceramics in medicine.
Peng, X., Wuhrer, R., Heness, G.L. & Yeung, W.Y. 2000, 'Rolling Strain Effects on the Interlaminar Properties of Roll Bonded Copper/Aluminium Metal Laminates', Journal of Materials Science, vol. 35, no. 0, pp. 4357-4363.
Metal laminates of copper/aluminium were prepared by roll bonding at 430 degrees C with various rolling strains. The effect of the rolling strain on the interface development and bond strength of the laminates was examined. It was found that as the rolling strain increased the bond strength of the laminates was generally enhanced in both as-rolled and sintered conditions. Critical post-rolling sintering conditions were found to exist for achieving optimum bond strengths of the laminates. It is evident that the development of optimum strength for the laminates is related to the formation of various intermetallic phases at the interface which is in turn determined by the diffusion activity of the metallic elements in the area. The greatest strength enhancement was generally observed to develop in the 60% rolled samples, suggesting that rolling strain of the roll bonding process may impose great influence on diffusion of the metallic elements. A higher copper content, without significant Kirkendall void formation, was found to build up in the interface area of the material, leading to development of strong interfacial phases. It is believed that a higher rolling strain of the roll bonding process has provided a greater area of physical contact between the bonded metals and imposed diffusion enhancement of the metallic elements across the interface. (C) 2000 Kluwer Academic Publishers.
Peng, X.K., Wuhrer, R., Heness, G. & Yeung, W.Y. 2000, 'Rolling strain effects on the interlaminar properties of roll bonded copper/aluminum metal laminates', Journal of Materials Science, vol. 35, no. 17, pp. 4357-4363.
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Metal laminates of copper/aluminum were prepared by roll bonding at 430 °C with various rolling strains. The effect of the rolling strain on the interface development and bond strength of the laminates was examined. It was found that as the rolling strain increased the bond strength of the laminates was generally enhanced in both as-rolled and sintered conditions. Critical post-rolling sintering conditions were found to exist for achieving optimum bond strengths of the laminates. It is evident that the development of optimum strength for the laminates is related to the formation of various intermetallic phases at the interface which is in turn determined by the diffusion activity of the metallic elements in the area. The greatest strength enhancement was generally observed to develop in the 60% rolled samples, suggesting that rolling strain of the roll bonding process may impose great influence on diffusion of the metallic elements. A higher copper content, without significant Kirkendall void formation, was found to build up in the interface area of the material, leading to development of strong interfacial phases. It is believed that a higher rolling strain of the roll bonding process has provided a greater area of physical contact between the bonded metals and imposed diffusion enhancement of the metallic elements across the interface.
Peng, X., Heness, G.L. & Yeung, W.Y. 1999, 'Effect of rolling temperature on interface and bond strength development of roll bonded copper/aluminium metal laminates', Journal Of Materials Science, vol. 34, no. 2, pp. 277-281.
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Copperperaluminium laminates were prepared by roll bonding at different temperatures between 350 and 500 degrees C. The effect of the roll bonding temperature on the interface reactions and bond strength development of the laminates was investigated. It
Heness, G.L., Ben-Nissan, B., Gan, L. & Mai, Y. 1999, 'Development of a finite element micromodel for metal matrix composites', Computational Materials Science, vol. 13, no. 4, pp. 259-269.
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A finite element micromodel has been developed based on real microstructures. The method of modelling is unique in that displacements calculated from large-specimen models are used as boundary conditions to model more accurately at the microstructural le
Peng, X., Wuhrer, R., Heness, G.L. & Yeung, W.Y. 1999, 'On the interface development and fracture behaviour of roll bonded copper/aluminium metal laminates', Journal of Materials Science, vol. 34, no. 9, pp. 2029-2038.
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Copperperaluminium laminates were prepared by roll bonding at 430 degrees C with a 60% rolling reduction in a single pass. Sintering treatments at temperatures between 300 and 500 degrees C were applied to the as-rolled laminates. The interface developme
Hadianfard, M., Heness, G.L., Healy, J. & Mai, Y. 1994, 'Fracture-toughness Measurements And Failure Mechanisms Of Metal-matrix Composites', Fatigue & Fracture Of Engineering Materials & Structures, vol. 17, no. 3, pp. 253-263.
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This paper compares the fracture toughness values obtained from two different specimen geometries, i.e. pre-cracked compact tension and chevron-notched short rod. The former is in widespread use, however, the latter has significant advantages in that no
Heness, G.L. 1989, 'Particulate matter reinforced phosphate bonded alumina bioceramics', Materials Science Forum, vol. 34-36, pp. 407-412.
Heness, G.L. 1988, 'Fabrication of phosphate bonded alumina bioceramic composites', Journal of Australasian Ceramic Society, vol. 24.
Heness, G. & Boow, J. 1980, 'SINTERING MECHANISMS OF SODIUM FLUORIDE.', Proceedings - Australian Ceramic Conference, pp. 163-167.
Assuming no effective change in the particle radius as the porosity is decreased, the initial slope corresponds with grain boundary diffusion via vacancy formation.