摘要
通过对一种镍基单晶合金进行中温不同应力条件下的蠕变性能测试及组织结构与断口形貌观察,研究了合金在蠕变期间的损伤及断裂机制。结果表明:合金在蠕变后期的变形机制是主、次滑移系的交替开动,主/次滑移系的多次交替开动,可在两滑移系交错区域的γ′/γ两相界面萌生裂纹;随蠕变进行,沿与应力轴垂直的γ′/γ两相界面发生裂纹的扩展,形成与<110>方向平行的正方形解理面,其中,裂纹在(001)面沿<110>方向扩展,与{111}二次解理面相截时,可终止裂纹扩展。这是使(001)解理面具有四方形特征的原因。由于蠕变期间在不同横断面发生多个微裂纹扩展,并在裂纹尖端沿较大剪切应力方向形成撕裂棱或发生二次解理,使多个裂纹连通,直至发生蠕变断裂。这是使合金蠕变断口呈现凹凸不平多层次解理特征的主要原因。
By means of creep properties measurement, microstructure and fracture morphology observation, the damage and fracturemechanism of a nickel-based single crystal superalloy was investigated during creep at moderate temperature. The results show that thedeformation mechanism of the alloy in the latter stage of creep is that the primary-secondary slipping systems are alternatively activated,and the initiation of the micro-crack may be generated on the interface of the cubical γ＇/γ phases in the intersection regions of two slipsystems. As creep goes on, the micro-crack may be propagated along the γ＇/γ phase interface which is perpendicular to stress axis, to formthe square cleavage plane parallel to 〈110〉 directions. Thereinto, when the propagation of the cracks on （001） plane is intersected with{ 111 } cleavage plane which is secondary activated, it may terminate the propagation of the crack. This results in the （001） cleavage planepossessing the square-like feature. Due to that the multi-cracks may propagate on different cross-section of the alloy during creep, and thetearing edge or secondary cleavage plane form along the bigger shearing stress direction at the crack tip, the multi-cracks are connectedeach other until the occurrence of creep fracture. It is thought to be the main reason of the uneven and multi-level cleavage characteristics
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2014年第5期1092-1098,共7页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51271125)
关键词
镍基单晶合金
蠕变性能
双取向滑移
裂纹萌生与扩展
蠕变断裂
nickel-based single crystal superalloy
creep property
double oriented slipping
initiation and propagation of crack
creepfracture
