一次时效温度对新型高强耐蚀GH925合金显微组织和力学性能的影响Effects of primary aging temperature on microstructures and mechanical properties of new corrosion-resistant alloy GH925 with high strength

为了研究一次时效温度对新型高强耐蚀GH925合金显微组织和力学性能的影响，利用热力学计算软件Thermo-Calc对合金中可能析出的平衡相及相组成进行计算并分析，采用超高分辨率场发射扫描电镜及附带能谱仪、扫描电镜和金相显微镜对合金中的析出相和冲击断口形貌进行观察。结果表明：一次时效温度对GH925合金中σ相和γ′相的析出行为影响显著；一次时效温度升高不仅会促进σ相在晶界上的大量析出并向晶内生长，而且会引起γ′相的粗化，导致合金强度和韧性降低；晶界σ相引起的脆化效应是导致沿晶断裂的根本原因。

In order to study the effect of primary aging temperature on the microstructures and mechanical properties of a new corrosion-resistant alloy GH925, the precipitated equilibrium phases and their compositions were calculated and analyzed by Thermo-Calc software, and the precipitated phases and impact fracture morphology were observed by ultra high resolution field emission scanning electron microscopy (FESEM) and energy dispersive spectrometry (EDS), scanning electron microscopy (SEM) and metallographic microscopy. The results show that the primary aging temperature has significant effect on the precipitation behaviors of σ phase and γ′ phase. The increase of primary aging temperature not only promotes the precipitation of a large number of σ phase at the grain boundary and its growth to the inner of the grain, but also leads to the coarsening of γ′ phase, giving rise to the decreases of strength and toughness. The root reason for the intergranular fracture is the embrittlement effect caused by σ phase at the grain boundary.

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