Enhanced mechanical property with refined microstructure of a novel γ-TiAl/TiB2 metal matrix composite (MMC) processed via hot isostatic press

Publication date: 5 March 2018
Source:Materials & Design, Volume 141
Author(s): Wei Li, Yi Yang, Ming Li, Jie Liu, Daosheng Cai, Qingsong Wei, Chunze Yan, Yusheng Shi
The microstructure design strategy is introduced to improve the mechanical property of a novel γ-Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB2 metal matrix composite (MMC) fabricated by hot isostatic press (HIP). With increasing the content of TiB2 from 0 to 3wt%, the average grain size, {001} maximum texture index and average schmid factor of HIP-processed Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB2 parts generally decrease from 27.4μm, 7.9 and 0.43 to 22.7μm, 4.1 and 0.38, in addition, the crystallographic texture transforms from the mixture of (001) and (111) orientations to a strong (101) orientation. The phases evolution mechanism in the HIP-processed Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB2 parts can be divided into four steps: first of all, β phase transforms to γ and α phases, then, a small amount of new phases of TiB and TiC emerge by the diffusion of Ti and C atoms, subsequently, the β and α orderly transform to B2 and α2, lastly, the B2, α2, TiB2, TiB and TiC uniformly distribute in the γ matrix. Both the tensile strength and strain of HIP-processed Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB2 components increase from 471.9MPa and 1.7% to 653.4MPa 2.1% with the increase of TiB2 content from 0 to 3wt%.

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