Microstructural investigation of stress-assisted alpha %26apos;%26apos;-alpha %26apos; phase transformation in cold-rolled Ti-7.5Mo alloy

作者：Chen Yen Chun; Ju Chien Ping; Lin Jiin Huey Chern^*

来源：Micron, 2014, 65: 34-44.

DOI：10.1016/j.micron.2014.04.005

• Ti-Mo alloy
• EBSD
• TEM
• XRD

The present study investigated the microstructure and stress-assisted alpha %26apos;%26apos;-alpha%26apos; phase transformation of a solution-treated Ti-7.5Mo alloy being cold-rolled with a series of different thickness reductions using transmission electron microscopic (TEM) and electron backscatter diffraction (EBSD) techniques. The EBSD/IPF results indicated a substantially random texture in ST sample. When the alloy was mildly cold-rolled, a texture toward %26lt; 1 0 (1) over bar 0 %26gt; preferred orientation was established, which gradually shifted toward (2 (1) over bar (1) over bar 0) with increased reduction in thickness. The TEM results indicated that substantially all fine platelets in the solution-treated (ST) sample had an orthorhombic alpha %26apos;%26apos; phase, and that a stress-assisted alpha %26apos;%26apos;-to-alpha%26apos; phase transformation took place when the alloy was cold-rolled, confirming the XRD results. In the mildly rolled (CR20) sample, the existence of alpha%26apos; phase could be easily identified, indicating that the stresses involved in the mild rolling process were sufficient to initiate the alpha %26apos;%26apos;-alpha%26apos; phase transition. On the other hand, in the heavily rolled (CR80) sample, the presence of residual alpha %26apos;%26apos; phase was still observed throughout the sample, indicating that the alpha %26apos;%26apos;-to-alpha%26apos; phase transition was never complete even after a severe cold rolling process. The SAD analysis indicated an orientation relationship, alpha%26apos;(1 (2) over bar1 0)//alpha %26apos;%26apos;(2 0 (2) over bar) and alpha%26apos; [0 0 0 1]//alpha %26apos;%26apos;[0 2 0], existing between the two phases.

• 出版日期2014-10