单晶高温合金用SiO_2基型芯力学性能及本构模型

Mechanical Properties and Constitutive Model of Silica-based Ceramic Core for Directional Solidification of Single Crystal Superalloy

对定向凝固单晶高温合金空心叶片用SiO_2基陶瓷型芯的力学行为进行了研究,得到了烧结样品S0和热处理样品S1、S2和S3的强度、弹性模量、应力-应变关系等实验结果。基于Weibull分布统计使用M-C (Mohr-Coulomb)判据结合实验结果,建立了符合定向凝固高温合金空心单晶叶片用SiO_2基陶瓷型芯的连续损伤本构模型,并给出了确定相关参数的方法。结果表明,经过1500℃高温热处理的SiO_2基陶瓷型芯样品力学性能、烧结程度均有所提高。使用损伤量D结合连续损伤本构模型公式和微观裂纹形貌,阐述了SiO_2基陶瓷型芯裂纹扩展与宏观断裂的演变关系。

The mechanical behaviors of silica-based cores for the directional solidification of single crystal superalloy hollow blades were investigated.The experimental results of strength,elastic modulus and stress-strain relationship of sintered samples S0 and heat treatment samples S1,S2 and S3 were obtained.Based on the Weibull distribution statistics,the continuous damage constitutive model of silica-based cores for the directional solidification of single crystal superalloy hollow blades was established by M-C(Mohr-Coulomb)criterion.The method of determining the relevant parameters of the continuous damage constitutive model was given.The results show that the mechanical properties and the degrees-of-sinter of silica-based core samples with heat treatment at 1500°C are improved.The relationship between the crack propagation and the macroscopic fracture of silica-based cores is described by the damage variable D in the constitutive model and microstructure.