大晶粒单相Ni-50Al金属间化合物高温塑性

Plasticity in Large-Grained Single-Phase Ni-50Al Intermetallics at High Temperature

摘要:

研究了原始晶粒尺寸为220 mm的正化学计量比单相Ni-50Al金属间化合物的高温变形行为及组织演变规律。结果表明，该合金在温度1000~1100 ℃，应变速率7.5×10-4~1×10-3 s-1范围内具有良好的高温塑性变形能力；在1075 ℃，应变速率为8.75×10-4 s-1时，最大延伸率可达139%。金相显微分析表明，原始大晶粒组织经高温塑性变形后显著细化；EBSD与 TEM分析表明，变形过程中小角度晶界持续产生，较小角度晶界向较大角度晶界不断演变，最终导致晶粒显著细化。显微结构综合分析表明，大晶粒Ni-50Al合金的高温塑性变形是由位错的交滑移与攀移等交互作用产生的连续动态回复和再结晶导致的。

Abstract:

High temperature deformation behavior and microstructure evolution of stoichiometry single phase Ni-50Al intermetallics with an initial grain size of 220 mm was investigated. Results show that the alloy exhibits good plastic behavior under initial strain rate from 7.5×10-4 to 1×10-3 s-1 in the temperature range of 1000-1100 ℃. A maximum elongation of 139% was obtained under initial strain rate of 8.75×10-4 s-1 at 1075℃. Optical metallography (OM) shows that the grains were refined during plastic deformation from initial 220 μm to less than 30 μm. Electron back-scattered diffraction（EBSD）and transmission electron microscopy (TEM) observations show that small-angle boundaries formed continuously during deformation, and changed to large-angle boundaries, resulting in finer grains finally. Microstructure analyses reveal that high-temperature plastic deformation could be attributed to continuously dynamic recovery and recrystallization (CDRR), which was caused by the interaction among gliding and climbing of dislocation.