颗粒间断裂在P/M镍基高温合金低周疲劳断口上的特征  

Characteristics of inter-particle rupture on LCF fractograph of P/M nickel-based superalloy

作　　者：张莹[1] 刘明东[1] 孙志坤[1] 张义文[1] 

机构地区：[1]钢铁研究总院高温材料研究所,北京100081

出　　处：《中国有色金属学报》2013年第4期987-996,共10页The Chinese Journal of Nonferrous Metals

基　　金：国家重点基础研究发展计划资助项目(2010CB631204);中俄政府间科技合作项目(CR14-20)

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。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 isostatie 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.

关 键 词：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 

分 类 号：TG132.32[一般工业技术—材料科学与工程]