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试验表明,[111]取向镍基单晶高温合金宏观滑移迹线符合六面体滑移特征,而微观位错滑移机制为八面体滑移。针对上述宏、微观现象,提出了一种“之”字形交滑移模型,使宏观六面体滑移迹线与微观位错的八面体滑移在该模型中得到了很好的统一。同时,在上述“之”字形交滑移变形机制的基础上,对[111]取向的拉压不对称特性进行了分析,提出一种位错分解方式,对[111]取向产生拉压不对称特性的微观机制进行了表征。最终,基于上述两种机理,建立了[111]取向镍基单晶高温合金的拉压不对称预测模型。该模型不仅能够对[111]取向镍基单晶高温合金屈服强度进行预测,而且可以表征屈服强度的拉压不对称特性,即压缩屈服强度大于拉伸屈服强度以及拉压不对称随温度升高愈加严重的现象。
Experiments show that the [111] oriented nickel-based single crystal superalloy macroscopically sliding trace coincides with the hexahedron slip feature, and the microscopic dislocation slip mechanism is octahedron slip. Aiming at the above macroscopic and microscopic phenomena, this paper presents a cross-slip model of “zigzag”, which makes the octahedral slip of macro-hexahedron and micro-dislocation very well unified in this model. At the same time, on the basis of the slip deformation mechanism of the above “” shape, the asymmetric tension and compression characteristics of [111] orientation are analyzed, and a dislocation decomposition method is proposed to produce tension and compression for [111] orientation The microscopic mechanism of asymmetric properties was characterized. Finally, based on the above two mechanisms, the asymmetric tension and compression prediction model of [111] oriented nickel-based single crystal superalloy was established. The model can not only predict the yield strength of [111] -oriented nickel-base single crystal superalloy but also characterize the tensile-compression asymmetric properties of yield strength, ie, the yield strength at compression is greater than the tensile yield strength and the asymmetric tensile-compression at elevated temperature The more serious the phenomenon.