PPB对镍基粉末高温合金裂纹扩展速率的影响

摘 要: 研究了直接热等静压（As-HIP）成形的一种镍基粉末高温合金中原始颗粒边界（PPB）对其裂纹扩展行为的影响。结果表明，粉末高温合金中的原始颗粒边界上析出的碳、氧化物会导致断裂韧性(KIC值)降低，使界面极易萌生裂纹;在裂纹扩展过程中发生沿颗粒间断开，改变扩展棱的走向，并加剧裂纹沿晶界扩展，使裂纹扩展速率增快；沿原始颗粒边界扩展的裂纹尖端的断裂韧度与边界析出物的物理性质、数量、尺寸密切相关，析出物排列越密集，KIC值越小，会加速裂纹在这些薄弱区扩展。

Influence of PPB on Fatigue Crack Growth Rate of PM Ni -Based Superalloy

Abstract: The effect of prior particle boundary (PPB) on the crack growth behavior of a powder metallurgy Nickel- based superalloy formed by direct hot isostatic pressing (As-HIP) was investigated. The results show that the precipitated carbon and oxide on the boundary of prior particles in the powder metallurgy superalloy will decrease the fracture toughness (KIC) and initiate cracks from the interface easily. In the course of crack propagation, fractures occur along the inter-particles, which changes the direction of extended edges, aggravates the propagation of cracks along the grain boundaries, and increase the crack growth rate. The fracture toughness of the crack tip extending along the boundary of prior particle is closely linked to the physical properties, number and size of the precipitates on the PPB. The denser the precipitates, the smaller the KIC, and the crack propagation accelerated in these weak areas.