定向凝固NiAl-15Cr合金的高温拉伸性能和韧脆转变条件
High Temperature Tensile Properties and Brittle-to-Ductile Transition of Directionally Solidified NiAl-15Cr Alloy
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摘要: 研究了定向凝固NiAl-15Cr合金的显微组织、高温拉伸性能和韧脆转变条件.结果表明:该合金显微组织为枝晶状,枝晶干为β-NiAl相、枝晶间为γ相和过渡层为γ′相;合金具有很好的高温塑性和高温强度,并在1 323 K时表现出类超塑性行为;同时它具有明显的韧脆转变温度,当应变速率为1.11×10-4 s-1时,韧脆转变温度为873 K,应变速率提高两个数量级后,韧脆转变温度升高约150 K.Abstract: The microstructure,high temperature tensile properties and brittle-to-ductile transition condition of directionally solidified NiAl-15Cr alloy had been investigated.The results show that the microstructure was dendritic shape.The dendrite arm was β-NiAl phase,γ phase was in interdendritic region and transient layer was γ′ phase.The alloy showed good plasticity and strength at high temperatures and superplasticity-like deformation behavior at 1 323 K.And it had obvious brittle-to-ductile transition temperature(BDTT),which was 873 K as the strain rate was 1.11×10-4 s-1.When the initial strain rate increased by two order of magnitude,the BDTT increased by approximate 150 K.