New insights into formation mechanism of interfacial twin boundary ω-phase in metastable β-Ti alloys
New insights into formation mechanism of interfacial twin boundary ω-phase in metastable β-Ti alloys
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亚稳态β-Ti合金界面孪晶界omega相形成机制的新见解
DOI：
10.1016/j.matchar.2020.110363
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发表时间：
2020-06-01
影响因子：
4.7
通讯作者：
Sun, Jun
中科院分区：
文献类型：
--
作者：
Chen, Wei;Cao, Shuo;Sun, Jun
亚稳β-钛（Ti）合金中的ω相变由于其内在的复杂性和改变力学性能的作用在过去十年中引起了极大的关注。据报道，在亚稳β-Ti合金中，沿沿着{332}（β）或{112}（β）孪晶界出现界面孪晶界（ITB）ω相。这种ITB ω相的形成被认为是由于逆α“马氏体转变为β马氏体以及随后沿孪晶界沿着的应力松弛引起的。在本研究中，Ti-10 wt.% Cr合金在初始组织中含有共沉淀物。实验发现，ITB同相的形成与有利的预先存在的一个共变体密切相关，而牺牲了其他三个兄弟姐妹，即，ω变体的重新定向。通过第一性原理计算，从ω-变体之间相互转化途径的能垒角度，进一步合理化了共重取向机制。这些发现为钛合金的Ω相变和进一步的塑性变形行为提供了基础性的认识。
The omega-phase transformation in metastable beta-titanium (Ti) alloys has attracted great attention in the past decade due to its intrinsic complexity and modifying mechanical properties. Interfacial twin boundary (ITB) omega-phase was reported to appear along {332}(beta) or {112}(beta) twin boundaries in metastable beta-Ti alloys. The formation of such ITB omega-phase was proposed to arise from the reverse alpha '' to beta martensitic transformation and subsequent stress relaxation along the twin boundaries. In this study, a new formation mechanism is revealed in Ti-10wt.%Cr alloy containing co-precipitates in the initial microstructure. It is experimentally found that the formation of ITB cophase is closely correlated with the favored pre-existing one co-variant at the expense of the other three-siblings, i.e., reorientation of omega-variants. The co-reorientation mechanism is further rationalized by first-principles calculation in terms of the energy barrier of transformation pathway between omega-variants. These findings advance our fundamental understanding to the omega-phase transformation and further plastic deformation behavior of Ti alloys.