密排六方结构金属多重孪晶再结晶晶体学织构弱化机制及控制因素研究

To improve deep-processing capacity of the HCP metals for the application of background to produce or process thin profile productions, systematic studies on the effects of weakening recrystallized texture by multiple deformation twinnings in HCP metals are necessary to carry out. As is well known, transilient orientations of twinnings differ from that of deformed matrix with certain angle/axis misorientation relationships of twinnings, as well as proliferate new interfaces, and that various types of deformaton twinning and productive variants exist in HCP metals, while appropriately strained conditions multiple twinning can be activated simultaneously. Conceivably, appropriate content and distribution of twinnings could weaken initial textures, and our previous studies have shown that deformation twinning recrystallization inherit the deflected orientations of twinnings at the early stage of recrystallization. Based on the results, to explore deformation and annealing or warm deformation parameters to get weak/random texture is conductive to satisfy the deep-processing thin profile productions of HCP metals with higher value c/a>1.60, for example, magnesium alloys; also HCP metals of lower value c/a<1.60, for example, zirconium alloys within nuclear reactor need adjust Hydride orientations to improve the needs of the service life. In this project proposal, we intend to select material of Magnesium alloys and Zircaloys, systematic studies will be implement to investigate the effect parameters of deformation twinning, and the behavior of twinning static recrystallization and dynamic recrystallization, and the mechanisms on nucleation of twinning recrystallization as well as the evolution of grain boundaries migration, and the formation principle of recrystallization texture, and then exam microstructure evolution during twinning recrystallizaiton. The main aim to do these investigations for the production of weak / random texture as well as uniform refinement micostructure, in order to provide a theoretical basis for enhancing thin profile of HCP metals, also to promote material the use of space has significant industrial application value.

以提高密排六方结构金属薄型材深加工能力为应用背景，系统研究六方结构金属多重形变孪晶再结晶弱化织构机制。众所周知，孪晶区别于基体突变新取向，并增殖新界面，六方结构金属形变孪晶种类多样，变体丰富，适当应变条件下多重出现。当这些孪晶达到适当含量和分布会弱化初始织构，本项目组前期研究表明，形变孪晶再结晶在初期遗传偏离基体的孪晶取向。在此基础上探索形变和退火或温形变参数以获得弱/随机织构，这是c/a>1.60金属如镁合金薄型材深加工的需要，也是c/a<1.60金属如核反应堆用锆合金改善氢化物取向提高服役寿命的需要。选择镁合金和锆合金作为研究材料，系统研究形变孪晶的影响参数，孪晶静/动态再结晶晶体学行为，孪晶再结晶形核机制及晶界演变规律、再结晶织构的形成规律，进而考察孪晶再结晶组织演变规律，为生产弱/随机织构以及均匀细小组织的六方结构金属薄材提供理论依据，对于提升材料使用空间有明显的工业应用价值。

密排六方结构(HCP)金属具有强烈各向异性，严重影响其薄型材的深加工，限制了工业应用范围，其中突出的是受到织构的影响。本项目旨在利用HCP金属具有丰富的孪晶及变体选择性，通过充分认清孪晶种类及其变体发生的影响因素来调控组织及织构，其中一种途径实现弱织构及均匀细化组织的调控。项目主要研究Mg、Zr、Zn三种典型的具有不同c/a值的HCP金属形变孪晶的影响参数，孪晶静/动态再结晶晶体学行为，孪晶再结晶形核机制及晶界演变规律、再结晶织构的形成规律，进而考察孪晶再结晶组织演变规律。获得重要的结果如下：验证了拉伸孪晶与压缩孪晶组织退火后再结晶晶粒的取向遗传的差异性；验证了孪生变体选择与局部应力状态的显著相关性；试验证实了工艺参数对组织结构及织构的影响规律，为生产弱/随机织构以及均匀细小组织的六方结构金属薄材提供理论依据，对于提升材料使用空间有明显的工业应用价值。