Contributions of microstructural features to the integrated hardness of TA15 titanium alloy

Analysis of the contributions of microstructural features to integrated property of TA15 titanium alloy is a crucial issue for microstructure design and obtaining desired material properties. To this end, various microstructural features, such as equiaxed primary alpha phase (alpha(p)) and its boundary (alpha(GB)), transformed beta matrix (beta(t)) consisting of alpha plate and residual beta phase (beta(base)) as well as the interface between them (beta(GB)) were obtained by different isothermal compression and heat treatment conditions. Nanoindentation and Vickers hardness tests were then performed on these features to investigate their contributions to the integrated property. It is found that the hardness of alpha(p) varies slightly with the compression and heat treatment temperatures. The hardness of beta(t) decreases while the hardness of integrated microstructure increases with increasing compression temperature. Moreover, the hardness values of beta(t) and integrated microstructure are larger when the heat treatment temperatures are higher. By considering the hardness and volume fraction of each microstructural feature, it is also found that the contributions of microstructural features to the integrated hardness increase in the order of alpha(GB), alpha(p), alpha(GB), beta(base). The contributions of alpha(p) and alpha(GB) decrease while those of beta(base) and beta(GB) increase with increasing compression temperature. In addition, the contributions of beta(base) and beta(GB) to the integrated hardness can be further adjusted by heat treatment under different temperatures. (C) 2015 Elsevier B.V. All rights reserved.