Shoichi Tokuda1 and Hiromichi Kawahara2
1Asada Fundamental Research Laboratory, Kobe Steel Ltd., Kobe
As a quantitative microsegregation study of titanium alloys by means of EPMA, following a previous report on Ti-Fe and Ti-Cr binary alloys, a series of experiments were carried out so as to investigate the effects of cooling rate from the β phase and contents of the alloying elements such as Mo and V for Ti-Mo and Ti-V binary alloys and commercial titanium alloys.
The results are as follows:
(1) The examination of parameters such as the segregation index, the effective distribution coefficient and the β stabilizing rate, showed that the genetic trend of the segregation for Mo was larger than V up to 4 wt% in content and was smaller than V over 10 wt% in content.
(2) There was a sort of a critical cooling rate under the effect of cooling rate from the β phase in microsegregation generation.
(3) The smaller the contents of β stabilizing elements, the stronger the genetic trend of microsegregation. And the trend was lessened with increasing degree of the β stabilizing in the alloys.
(4) The genetic trend of microsegregation of Mo and V became stronger in co-existence with Al.
(5) Electron absorption images of Ti-Mo alloys showed that the microsegregation was distributed in a certain small area. V can be presumed to have the same tendency as Mo.
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