Surface modification of titanium and titanium alloys: Technologies, developments, and future interests

Combustion synthesis is widely used for preparing various refractory and hard materials, including alloys, intermetallics, ceramics, and cermets. The unique reaction condition in combustion synthesis with extremely-high temperature and fast heating/cooling rate offers the products interesting microstructures and superior mechanical properties. In comparison with conventional powder metallurgy approaches, combustion synthesis exhibits the advantages of short processing time, less energy consumption, and lower cost, thus providing a more efficient way to produce refractory and hard materials. This article reviews recent progress in combustion synthesis of refractory and hard materials, with an emphasis on the results reported in the last decade. Both the synthesis of powders and direct fabrication of bulk materials are discussed. For the synthesis of powders, results in two aspects are reviewed, viz. synthesis of ultrafine and especially nano-sized powders by thermal reduction reactions or post chemical etching, and synthesis of nitride and carbide powders in air. For direct fabrication of bulk materials, two techniques are involved, viz. combustion synthesis with simultaneous densification assisted by a mechanical or gas pressure, and combustion synthesis casting in a high-pressure Ar atmosphere or in a high-gravity field.

http://acm.ipc.cas.cn/yjdt/201310/P020131015422453081926.pdf

Combustion synthesis of refractory and hard materials: A review

Chemical composition, microstructure and sintering temperature modifications on mechanical properties of TiC-based cermet – A review

β-type titanium (Ti) alloys have attracted a lot of attention as novel biomedical materials in the past decades due to their low elastic moduli and good biocompatibility. This article provides a broad and extensive review of β-type Ti alloys in terms of alloy design, preparation methods, mechanical properties, corrosion behavior, and biocompatibility. After briefly introducing the development of Ti and Ti alloys for biomedical applications, this article reviews the design of β-type Ti alloys from the perspective of the molybdenum equivalency (Moeq) method and DV-Xα molecular orbital method. Based on these methods, a considerable number of β-type Ti alloys are developed. Although β-type Ti alloys have lower elastic moduli compared with other types of Ti alloys, they still possess higher elastic moduli than human bones. Therefore, porous β-type Ti alloys with declined elastic modulus have been developed by some preparation methods, such as powder metallurgy, additive manufacture and so on. As reviewed, β-type Ti alloys have comparable or even better mechanical properties, corrosion behavior, and biocompatibility compared with other types of Ti alloys. Hence, β-type Ti alloys are the more suitable materials used as implant materials. However, there are still some problems with β-type Ti alloys, such as biological inertness. As such, summarizing the findings from the current literature, suggestions forβ-type Ti alloys with bioactive coatings are proposed for the future development.

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Recent Development in Beta Titanium Alloys for Biomedical Applications

As interfaces play a more important role in high-volume-fraction ceramic/metal composites because of containing more hetero-phase interfaces, it is a great challenge to control the interfaces in such composites to balance their strength and plasticity and to obtain high performances. In this work, 50–60 vol% (TiC + TiB2)/Al composites were fabricated in Al–Ti–B4C system via a one-step method of reaction and densification, and their interface bonding and mechanical properties were compared with those of in-situ TiC/Al composites. Apparently, the defects, such as interfacial discontinuity, macro-pores, coarsening and agglomeration of particles, caused by increased ceramic content in the TiC/Al composites, are eliminated in the (TiC + TiB2)/Al composites using Al–Ti–B4C system. The 60 vol% (TiC + TiB2)/Al composite exhibits significantly enhanced mechanical properties, i.e. 70.5%, 60.7% and 69.8% respectively higher yield strength, ultimate compressive strength and plastic strain than 60 vol% TiC/Al composite. Such enhanced mechanical properties are attributed to the improvement in interface bonding strength and therefore the increase in the energy dissipation of crack propagation. The formation of enhanced interface in the (TiC + TiB2)/Al composites results from the reduction in the reaction heat in the Al–Ti–B4C system, improved crystallographic match and improved adhesion work between ceramic particles and matrix. This work may provide a new idea for the design and control of interfaces in high-volume-fraction ceramic-metal composites.

Interface formation and bonding control in high-volume-fraction (TiC+TiB2)/Al composites and their roles in enhancing properties

Compression properties and abrasive wear behavior of high volume fraction TiCx–TiB2/Cu composites fabricated by combustion synthesis and hot press consolidation

Compression properties and work-hardening behavior of Ti2AlC/TiAl composites fabricated by combustion synthesis and hot press consolidation in the Ti–Al–Nb–C system

Effects of alloy elements (Mg, Zn, Sn) on the microstructures and compression properties of high-volume-fraction TiCx/Al composites

In situ high volume fraction (50–70 vol.%) TiC x /Al composites were successfully fabricated by combustion synthesis and hot press consolidation in an Al–Ti–C system. Microstructure characterization of the TiC x /Al composites shows relatively uniform distribution of the TiC x particles with the particle size in the range of about 1–5 μm. All of the yield strength ( σ 0.2 ), hardness and abrasive wear resistance of the TiC x /Al composites increase with the increase in the TiC x content, and the σ UCS firstly increases and then decreases. The σ 0.2 , σ UCS , fracture strain ( ɛ f ) and hardness of the 70 vol.% TiC x /Al composite are 576 MPa, 744 MPa, 3.09% and 253.5 ± 6 Hv, respectively. The abrasive wear resistance of the 70 vol.% TiC x /Al composite is about 4 times higher than that of the cast hypereutectic Al–Si alloy when the applied load is no more than 25 N and the Al 2 O 3 abrasive particle size is no more than 20 μm.

Jianbang Lu

Papers

Compression properties and abrasive wear behavior of high volume fraction TiCx–TiB2/Cu composites fabricated by combustion synthesis and hot press consolidation

Compression properties and work-hardening behavior of Ti2AlC/TiAl composites fabricated by combustion synthesis and hot press consolidation in the Ti–Al–Nb–C system

Effects of alloy elements (Mg, Zn, Sn) on the microstructures and compression properties of high-volume-fraction TiCx/Al composites

High volume fraction TiCx/Al composites with good comprehensive performance fabricated by combustion synthesis and hot press consolidation

Effect of Ta addition on the microstructures and mechanical properties of in situ bi-phase (TiB2-TiCxNy)/(Ni-Ta) cermets