置氢Ti6Al4V合金的微观组织演变规律

为研究置氢Ti6Al4V合金的高温加工改性机理,从微观组织的角度对合金进行了对比分析.利用OM、SEM、XRD等研究了置氢对Ti6Al4V合金变形前后微观组织演变的影响.研究结果表明:氢的加入不仅使置氢Ti6Al4V合金中β相比例明显增大,而且改变了α相与β相之间的电势差,在氢含量为0.3%~0.5%两相颜色将发生互换,氢含量增加到0.50%以上时,合金中将出现面心立方结构的δ氢化物;随氢含量的增加,合金超塑拉伸变形后的组织由α+β两相等轴晶粒变为粗大的β晶粒,造成α与β界面的协调能力下降,并改变了合金的变形机制.

Microstructure transition of hydrogenated Ti6Al4V alloy

To research the mechanism of capability improvement at high temperature for hydrogenated Ti6Al4V alloy,contrastive analysis on its microstructure was carried out.The microstructure transition in hydrogenated Ti6Al4V alloy before and after deformation was investigated by means of OM,SEM and XRD.The results show that the addition of hydrogen can not only increase the amounts of β phase rapidly,but also change the electric potential difference between α phase and β phase,thus light and shade contrast interchanges when the hydrogen content reaches about 0.3wt%～0.5wt%.There are δ titanium-hydrides precipitated in the alloy containing hydrogen of 0.50wt%.With the increase of hydrogen content,equiaxed grains turn to coarse β grains after superplastic deformation.The coarsening β phase may deteriorate the coordination of the interface between α phase and β phase and change the deformation mechanism.