摘要
Since titanium has high affinity for hydrogen and reacts reversibly with hydrogen,the precipitation of titanium hydrides in titanium and its alloys cannot be ignored.Two most common hydride precipitates in α-Ti matrix areγ-hydride and δ-hydride,however their mechanisms for precipitation are still unclear.In the present study,we find that both γ-hydride and δ-hydride phases with different specific orientations were randomly precipitated in the as-received hot forged commercially pure Ti.In addition,a large amount of the titanium hydrides can be introduced into Ti matrix with selective precipitation by using electrochemical treatment.Cs-corrected scanning transmission electron microscopy is used to study the precipitation mechanisms of the two hydrides.It is revealed that the γ-hydride and δ-hydride precipitations are both formed through slip+shuffle mechanisms involving a unit of two layers of titanium atoms,but the difference is that the γ-hydride is formed by prismatic slip corresponding to hydrogen occupying the octahedral sites of α-Ti,while the δ-hydride is formed by basal slip corresponding to hydrogen occupying the tetrahedral sites ofα-Ti.
基金
This work was supported financially by the National Natural Science Foundation of China(Nos.51621003,11374028and U1330112)
the Scientific Research Key Program of Beijing Municipal Commission of Education(No.KZ201310005002)
the Beijing Municipal Found for Scientific Innovation(No.PXM2019014204500031)
the Foundation on the Creative Research Team Construction Promotion Project of Beijing Municipal Institution(No.IDHT20190503)。
