在760℃下, 对22种不同晶体学取向的DD407单晶高温合金进行了拉伸断裂实验, 得到了产生0.2%塑性变形时对应的屈服强度. 使用SEM观察了各取向试样的断口形貌, 并使用XRD辨别了断口的晶体学特征. 结果表明, 靠近[111]取向的试样变形时启动立方滑移系, 而其它取向的试样均启动八面体滑移系. 使用LCP模型建立并分析了屈服强度与晶体取向的关系. 结果表明, 在760℃下, DD407单晶高温合金发生八面体滑移变形时, 屈服强度与晶体取向的关系符合LCP模型; 而沿[111]取向发生立方滑移变形时, 屈服强度与取向的关系偏离LCP模型. 基体γ相的参与变形导致LCP模型应用于γ/γ’双相的单晶高温合金时, LCP参数项b₂为正.

The yield strength, corresponding to 0.2% plastic deformation, of superalloy single crystal DD407 with 22 different orientations were measured at 760℃ to investigate the orientation dependence of yield strength for this superalloy. The facets of fractured specimens were observed by scanning electron microscopy and their crystallographic characters were identified with the aid of X-ray diffractometer. The results indicated that specimens near [111] were deformed by cubic slip systems,and the rests were deformed with octahedral slip systems. The orientation dependence of yield strength was established and analyzed by an LCP-model. It showed that the yield strength of DD407 specimens deformed by octahedral slip accorded with LCP-model, whereas those deformed by cubic slip, such as [111] crystals, deviated from LCP-model. A close inspection of the LCP parameters suggests that, in dual-phase γ/γ’ crystals, the effect of γ matrix must be responsible for the positive sign of b₂ term which is negative in mono-phaseγ’ crystals.