TG6钛合金冷却过程的块状转变机制研究

在近α型TG6钛合金两相区淬火过程中,对初生α相αP周围形成的块状组织αm进行表征研究,块状组织αm与αP存在明显的界面,合金元素Al、Sn和Zr浓度介于αP和β基体之间,EBSD分析结果表明αm取向与αP保持一致。在冷却过程中,αP周围β基体中合金元素扩散受到限制,进而在局部过渡成分区域通过扩散转变形成αm组织。当固溶温度从1040℃提高至1060℃,同时保温时间从30 min减少为5 min,溶质元素扩散受限,αm体积分数从5.2%提升至30.7%。

Massive Transformation Mechanisms in TG6 Titanium Alloy During Cooling

A kind of massive microstructureαm along the primaryαphase(αP)has been characterized in the microstructure quenched from theα+βphase field.The obvious interface betweenαm andαP can be found under the optical observation,and the concentrations of Al,Sn and Zr elements inαm are in between that of theαP andβmatrix,but the orientation of theαm keeps consistent with that of theαP as evidenced by EBSD analysis.The appearance of theαm is considered as the result of limited diffusion controlled transformation from theβphase during the cooling,because theαm initiates from theα/βinterface and keeps the consistent orientation withαP,and the growth is limited around theα/βinterface.As the diffusion is limited by decreasing the solution periods from 30 min to 5 min,and the dissolving ofαP is accelerated by increasing the solution temperature from 1040 C to 1060 C,the volume fraction ofαm increases from 5.2%to 30.7%significantly.