置氢对Ti6Al4V合金室温组织的影响

Influences of hydrogenation on room temperature microstructure of Ti6Al4V alloy

通过在钛合金中引入临时元素氢,可以改变钛合金的相组成,进而改变钛合金的力学性能和加工性能.利用OP、XRD和TEM研究了固态置氢后Ti6Al4V合金的微观组织变化.研究表明:随氢含量的增加,合金中的β相含量增加,在置氢0.302%及0.490%(质量分数)的试样中发现面心立方(fcc)的氢化物δ,及大量的斜方结构的马氏体α",未发现亚稳态的氢化物γ.提出了一种基于扩散的由βH共析转变生成α及fcc结构的片状氢化物δ的机制,并指出氢的引入可能诱发马氏体转变.

Hydrogen is usually used as a temporary component to adjust the mechanical properties and the processing abilities of titanium alloys through modifying the microstructure. The paper investigated the microstruc-ture of Ti6Al4V alloy after hydrogenation at solid state by OP、XRD and TEM. It was shown that the content of β phase increases with hydrogen. There are δ titanium hydride ( fcc structure, a=0. 444 nm) plates precipitated in the specimens containing hydrogen 0. 302wt% and 0. 490wt% . Simultaneously, a mass of orthorhom-bic martensite α' has been found in the specimens containing hydrogen 0. 302wt% and 0. 490wt% as well as δ hydride. However, metastable titanium hydride γ( fct structure, c/a = 1.02/1.09) has not been found. This paper presents one eutectoid transformation mechanism from βH to δ hydride and α based on diffusion transformation theory. The martensite transformation induced by hydrogen has also been discussed.