Effects of rolling deformation on microstructure orientations and tensile properties of TiB/(TA15-Si) composites

To explore the orientation evolution and interfacial characteristics under the beta-phase region, rolling deformation with different reduction ratios of 40- 90% was carried out by hot-pressing sintering and multi-pass hot rolling on a series of TiB whiskers reinforced Ti-6.5Al-2Zr-1Mo-1 V-0.3Si (TiB/(TA15-Si)). As rolling deformation increased, the matrix exhibited slight refining and distortion within lamella alpha + beta, and a stronger T-type alpha texture was gradually formed. A portion of Burgers Orientation Relation (BOR) between parent beta and alpha phases gradually disappeared due to a decrease in rolling temperature and post deformation after phase transformation. Meanwhile, TiB rotated and presented an intenser orientation of {100} (010). Silicides heterogeneously precipitated along the alpha/beta phase boundaries both near and away from TiB. Silicide/matrix remained fine interfaces owing to resolution and reprecipitation. Finally, the ultimate strengths at room temperature were monotonously improved with the increase of deformation due to strong work hardening. And an anisotropy of tensile properties was found under large deformation. The composite tensioned along the transverse direction (TD) can exhibit higher strength and lower ductility due to mutual competition of TD strengthening by T-type texture and RD strengthening by TiB distribution, especially at 600 degrees C. The fracture paths of as-rolled composites were discussed in detail.

Automated summary

This study investigated the orientation evolution and interfacial characteristics of TiB whiskers reinforced Ti alloy under different reduction ratios of rolling deformation. It was found that the ultimate strength of the material increased with deformation, but anisotropy of tensile properties was observed.