Purpose This paper aims to present a broad review of near-a titanium alloys for high-temperature applications. Design/methodology/approach Following a brief introduction of titanium (Ti) alloys, this paper considers the near-α group of Ti alloys, which are the most popular high-temperature Ti alloys developed for a high-temperature application, particularly in compressor disc and blades in aero-engines. The paper is relied on literature within the past decade to discuss phase stability and microstructural effect of alloying elements, plastic deformation and reinforcements used in the development of these alloys. Findings The near-a Ti alloys show high potential for high-temperature applications, and many researchers have explored the incorporation of TiC, TiB SiC, Y2O3, La2O3 and Al2O3 reinforcements for improved mechanical properties. Rolling, extrusion, forging and some severe plastic deformation (SPD) techniques, as well as heat treatment methods, have also been explored extensively. There is, however, a paucity of information on SiC, Y2O3 and carbon nanotube reinforcements and their combinations for improved mechanical properties. Information on some SPD techniques such as cyclic extrusion compression, multiaxial compression/forging and repeated corrugation and straightening for this class of alloys is also limited. Originality/value This paper provides a topical, technical insight into developments in near-a Ti alloys using literature from within the past decade. It also outlines the future developments of this class of Ti alloys.

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The paper discusses the effects of B4C particle (B4Cp) content on the microstructure and high-temperature oxidation resistance of B4Cp/Ti-5.4Al-4.03Mo-3.93V-2.37Cr-0.01Zr composite prepared by powder metallurgy. The results demonstrate that grain size of the composites decreases by increasing reinforcement content from 1 to 3 wt.%, suggesting that B4Cp can refine grain of the materials. For the composites with increasing B4Cp content from 0 to 3 wt.%, the apparent porosity increase from 3.23 to 6.89%, indicating that the density of materials decreased with the increase of B4CP content. In addition, the hardness of the materials have been greatly improved. Comparing to the substrate 434.02 HV, the 1, 2, and 3 wt.% B4CP specimens are increased by 37.2%, 57.5%, and 84.7%, respectively. The weight of the oxidation product is reduced and the oxidation rate is slowed down, as the B4CP content increases. Moreover, the thickness of the oxide layer is greatly reduced, and the thickness of oxidation layer in composites with 0, 1, 2 and 3 wt.% B4CP specimens were 60, 55, 47 and 40 μm, indicating that B4CP can improve the high-temperature oxidation resistance.

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