单晶态Mo5SiB2合金力学行为各向异性机理研究

With a brittle-to-ductile transition (BDT) in the range of 1000-1200℃, the intermetallic Mo5SiB2 (T2) alloy is regarded as a extremely competitive ultra-temperature structural material, and its single crystals display mechanical anisotropy during high-temperature deformation. When the deformation behaviors on different oriented T2 single crystals are systematically investigated in the temperature range of 1000-1600℃, observations and characterization are achieved to clarify slip bands on the surfaces of tensile samples, and to clarify the dislocations in deformed microstructures. More attentions will be focused on the evolutions of dislocation configuration, mobility and interaction with different crystal orientations, temperatures and strain rates, with the purpose of studying their effects on flow stress, yield phenomenon and work hardening, and then the microscopic mechanism of Mo5SiB2 mechanical anisotropy will be revealed. The obtained results will be beneficial to explain the wide temperature range of BDT and abnormal temperature effect of yield stress, and even to develop the structural materials operative at high temperatures above 1200℃.

金属间化合物Mo5SiB2（T2）合金被认为是极具竞争力的新一代超高温结构材料，在1000-1200℃温度区发生脆-韧转变，其单晶态在高温变形过程中力学行为呈现出明显的各向异性。本项目拟在系统考察不同取向T2相单晶高温（1000-1600℃）变形行为的基础上，通过对拉伸试样表面滑移带光镜以及变形组织中位错的观察和表征，着重研究位错类型、运动与反应及其随晶体取向、温度、应变速率的变化，以及这种变化对流变应力、屈服现象、加工硬化能力等的影响，从基础层面揭示T2相力学行为各向异性的微观机理，进而为解释金属间化合物的宽泛脆-韧转变温度及屈服应力反常温度效应提供理论基础，对发展超高温（>1200℃）结构材料具有学术价值和重要意义。

金属间化合物Mo5SiB2合金是潜在的超高温结构材料，在1000~1200℃温度区发生脆-韧转变，其单晶态在高温变形过程中力学行为呈现出明显的各向异性。本项目在系统考察不同取向Mo5SiB2相单晶高温（1000-1600℃）变形行为的基础上，通过对压缩试样表面滑移带的光学电镜观察以及变形组织中位错的透射电镜观察，着重研究了位错类型、运动与反应及其随晶体取向、温度、应变速率的变化，以及这种变化对流变应力、屈服现象、加工硬化能力等的影响，从基础层面揭示了Mo5SiB2相力学行为各向异性的微观机理，进而为解释了金属间化合物的宽泛脆-韧转变温度及屈服应力反常温度效应提供理论基础，对发展超高温（>1200℃）结构材料具有学术价值和重要意义。