Clarification of the origin of embrittlement of beta-Ti alloys, and the improvement of their mechanical properties by focusing on the deformation induced omega-phase transformation

首次在一种ω-Ti单晶(Ti-35Nb-10Ta-5Zr)中发现了β相在循环变形过程中动态析出的特殊现象。通过改变循环形变过程中位错运动的伯格斯矢量，可以控制形成的ω相的晶体取向(变量)。这表明循环形变诱发ω相的形成机制与位错的往复运动直接相关。此外，我们还阐明了含有取向β相的ω-Ti单晶表现出强烈的塑性各向异性，这与加载方向有关，这强烈地影响了析出ω相的钛晶体的脆性特征。

We found the peculiar phenomenon of the dynamical precipitation of ω-phase during the cyclic deformation in a kind of β-Ti single crystals (Ti-35Nb-10Ta-5Zr) for the first time. We clarified that the crystal orientation (variant) of the formed ω-phase can be controlled by changing the Burgers vector of the dislocation moving during the cyclic deformation. This demonstrates that the formation mechanism of the cyclic deformation induced ω-phase is directly related to the to-and-fro motion of dislocations. In addition, we clarified that the β-Ti single crystal containing the oriented ω-phases shows strong plastic anisotropy depending on the loading orientation, which strongly affects the brittle features of the Ti-crystal in which the ω-phases were precipitated.