(钢铁研究总院 高温材料研究所，北京 100081)
摘 要: 粉末冶金(P/M)合金中由于原始颗粒边界(PPB)的存在，在力学性能试样断口上呈现颗粒间断裂。通过SEM、TEM、AES等手段对采用等离子旋转电极(PREP)制粉+直接热等静压(HIP)成形工艺的一种P/M镍基高温合金低周疲劳(LCF)断口上颗粒间断裂的形貌和类型进行了表征和分析，讨论了PPB的起因及其与疲劳裂纹在颗粒间萌生、扩展断裂机制的关系和颗粒间断裂对疲劳寿命的影响。结果表明：PREP+HIP工艺成形的镍基合金中的PPB由多种综合因素造成；PPB降低了合金的断裂韧性，直接影响颗粒间断裂程度；在LCF断口上，单颗粒成为裂纹源的占颗粒间断裂断口总数的67%，多颗粒裂纹源占17%，其他占16%；颗粒间断裂在LCF断口上的分布表征分为4级；颗粒间断裂越严重，对合金疲劳寿命影响越大。
关键字: 粉末冶金高温合金；原始颗粒边界；颗粒间断裂；低周疲劳断口
（Central Iron and Steel Research Institute, High Temperature Material Institute, Beijing 100081, China）
Abstract:The mechanical property of sample fractures shows inter-particle ruptures due to the existence of prior particle boundary (PPB) in P/M superalloys. The inter-particle rupture morphological characterization and type on low cycle fatigue (LCF) fracture of a nickel-based P/M superalloys by plasma rotating electrode process (PREP) plus hot isostatic press (as-HIP) were analyzed by SEM, TEM and AES. The causes of PPB formation and relationships between PPB and mechanism of fatigue crack initiation and crack propagation at inter-particle, as well as the effect of inter-particle rupture on LCF life, were discussed. The results show that PPB in P/M nickel-based superalloys processed by PREP +HIP is caused by many composite factors, PPB reduces the fracture toughness, and directly affects the degree of inter-particle rupture, a single particle to be the crack origin on LCF fracture accounts for 67% of the total fractures, multi-particle 17%, other 16%. The distribution characterization of inter-particle fracture on LCF fractograph can be divided into four grades, the more serious inter-particle fractures affects fatigue lives more.
Key words: P/M superalloy; prior particle boundary; inter-particle rupture; low cycle fatigue fracture
