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采用OM,SEM和TEM研究了一种Ni-Cr-W-Fe合金在760℃长期时效过程中的显微组织变化,测试了合金室温和高温力学性能,对拉伸断口进行了分析.结果表明,1100℃固溶后合金平均晶粒尺寸约为80 mm,晶内包含退火孪晶.760℃时效后合金中析出M23C6和g’相.g’相尺寸约为29 nm,体积分数约为19%.760℃长期时效后,g’颗粒平均尺寸与时间t满足Ostwald方程.固溶态合金具有优异的室温塑性,拉伸断口具有韧性断裂形貌.时效态合金室温屈服强度明显增加,塑性下降.随760℃保温时间延长,合金室温和高温屈服强度缓慢降低.与时效态合金相比,1000~3000 h时效后的合金室温塑性降低,高温塑性维持在15%左右,与时效态基本相当.
The microstructure changes of a Ni-Cr-W-Fe alloy at 760 ℃ for a long time were studied by OM, SEM and TEM. The mechanical properties at room temperature and high temperature were tested and the tensile fracture was analyzed. , The average grain size of the alloy after solution treatment at 1100 ℃ is about 80 mm, and the inclusions in the crystal contain annealed twins. The M23C6 and g ’phases are precipitated in the alloy after aging at 760 ℃, the phase size of g’ is about 29 nm and the volume fraction is about 19 After aging at% .760 ℃, the average size and time t of g ’particles satisfy the Ostwald equation. The solid solution alloy has excellent room temperature ductility and the tensile fracture has a ductile fracture morphology. The yield strength at room temperature of the aged alloy increases obviously and the ductility decreases With the prolongation of holding time at 760 ℃, the yield strength of the alloy at room temperature and high temperature decreased slowly, compared with the aged alloy, the room temperature plasticity of the alloy after 1000 ~ 3000 h aging decreased and the plasticity at high temperature maintained at about 15%.