金属铍高低温变形机制及动/静态组织演化

The deformation behaviors of metal beryllium will be systemically studied in this work for acquiring the competition relationships between various deformation mechanisms (basal slip, prismatic slip, twin deformation and grain boundary sliding, etc.) and their activation conditions at different temperatures. The effects of impurities on various deformation mechanisms will be simultaneously clarified. And then the contribution of various deformation mechanisms to beryllium ductility will be ascertained at different temperatures. Furthermore, dynamic/static softening behaviors of deformed microstructure will be systemically investigated in order to define dynamic/static recrystallization (DRX/SRX) mechanisms of the metal beryllium with high stacking fault energy, and to reveal the external deformation conditions and influence factors of microstructure for beryllium occurring DRX/SRX. The constitutive relationship model which can describe high temperature flow behavior (DRX temperature zone) of the metal beryllium and dynamic models which can represent DRX/SRX microstructure evolution of the metal beryllium will be developed. As a result, it will be achievable to accurately appraised the hot workability of the metal beryllium at different temperatures and propose grain fining technologies of the metal beryllium by controlling DRX/SRX behaviors. The work will be provide a theoretical basis for designing or optimizing press-working technology of the metal beryllium and bring a new research idea for manufacturing ultra-fine grain beryllium.

通过对不同温度下金属铍变形行为，及其形变组织动/静态软化行为的系统研究，解析不同温度下铍各变形机制（基面滑移、柱面滑移、孪晶变形和晶界滑移）之间的竞争关系和激活条件，揭示杂质对它们的影响，明确不同温度下各变形机制对铍塑性的贡献；探明高层错能金属铍动/静态再结晶机理及其外部变形条件和内部组织影响因素，建立铍高温（动态再结晶温度区）流变行为本构方程及动/静再结晶组织演化动力学模型；正确评价不同温度下铍的热加工性，提出金属铍可控动/静态再结晶的细晶化工艺。为铍压力加工技术开发工艺设计或优化设计提供基础数据，并为铍材超细晶化提供新的研究思路。

本项目通过对不同温度下金属铍变形及软化行为的系统研究，阐明了不同温度下铍各变形机制（基面滑移、柱面滑移、孪晶变形）的竞争关系，高温时仍保持{0001}基面滑移和{10-12}类孪生反常变形行为。发现了金属铍独特的静态再结晶行为，即再结晶晶粒首先在{10-12}<10-11>拉伸孪晶界处形核而非晶界处，BeO 杂质对原始晶粒晶界迁移的钉扎作用是孪晶界弓出形核先于晶界弓出形核的根本原因，因此本项目进一步拓展研究了铍中BeO杂质形态和分布在整个制备过程的中演化机理；而金属铍动态再结晶行为更为独特，再结晶晶粒尽管表现为在晶内同时大量密集形成，却与基体呈特定取向关系，且关系十分复杂，性质上也分为两类，一类为铍低Σ值重位点阵（CSL）晶界，一类取向轴为铍<2-1-10>滑移方向，既不是经典不连续动态再结晶，也不符合连续动态再结晶理论。同时，本项目还着力解析了金属铍工艺参数对再结晶组织演化的影响，建立了金属铍再结晶本构模型，为准确控制金属铍的再结晶组织奠定基础。目前，项目部分研究成果已经用于生产实践，指导我国金属铍轧制生产工艺更新和组织细晶化。