A new Ni based powder metallurgy superalloy was prepared by hot isostatic pressing, hot extrusion (HE) and 1 130 ℃/1 h heat treatment using Ni based alloy powder as raw material. The low cycle fatigue behavior including the microstructure of the pristine alloy, cyclic stress response and fracture morphology of the alloy were studied by a LCF test under atmospheric environment at 750 ℃. The results indicate that the previous particle boundary (PPB) appears after hot isostatic pressing, which is mainly consisted of coarse γ′ and fine carbon oxides. After HE and heat treatment, PPB disappears and grains refine to 7.5 μm. There are three types of γ′ phase after heat treatment, coarse γ′ phase on boundary, nearly spherical medium size γ′ phase and dispersed fine spherical γ′ phase intragranular. The low cycle fatigue fracture mode of the alloy is mainly intergranular fracture, and the grain surface of the fracture surface has different degree of oxidation.%以镍基合金粉末为原料,通过热等静压与热挤压以及1130 ℃/1 h条件下热处理,制备一种新型镍基粉末冶金高温合金,在750 ℃大气环境下对该合金进行低周疲劳试验,分析合金疲劳前的微观组织、低周疲劳循环应力响应行为和断口形貌.结果表明,镍基合金粉末经过热等静压后,出现原始颗粒边界,主要为粗大的γ′相和细小的碳氧化物.热等静压坯体经过热挤压并进一步热处理后,原始颗粒边界消失,晶粒细化到7.5 μm左右,合金的γ′相主要有3类:晶界上的粗大γ′相、晶内近球形的中等尺寸γ′相和弥散分布的球形细小γ′相.该合金的低周疲劳断裂方式以沿晶断裂为主,断裂面的晶粒表面有不同程度的氧化.
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