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Investigation on Deformation and Fracture Behavior of Sintered Materials from a viewpoint of Composite

从复合材料的角度研究烧结材料的变形和断裂行为

基本信息

批准号：
61550053
负责人：
TOHOGO Keiichiro
金额：
$ 1.28万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

The sintered materials are macroscopically homogeneous but microscopically heterogeneous. So, deformation and fracture behavior of the sintered materials is controlled by the heterogeneity. In this investigation, tests of WC-Co hardmetals have been carried out on the deformation and fracture behavior, and a mechanical model for estimation of the deformation of two-phase sintered materials has been devaloped. Fracture mechanism of WC-Co hardmetals was investigated based on the results of tensile tests, compressive tests and fatigue tests, and fracture surface was characterized based on SEM observation and EDX analysis. Taking account of the experimental results, the mechanical model of two-phase sintered materials, which can predict not only overall elastic moduli and overall instantaneous elastic-plastic moduli but also microscopic stress/strain of each phase, was developed. This model was applied to estimation of the deformation behavior of WC-Co hardmetals with various volume fraction of Co. The analytical results of the overall elastic moduli and the overall stress-strain relation under uniaxial tensile tests agreed well with the experimental results. The variation of the transverse rupture strength of WC-Co hardmetals, as a function of Co volume fraction, was explained from a viewpoint of microscopic stress/strain. Further, macroscopic stress/strain field and microscopic stress/strain field around a crack tip in WC-Co hardmetals was analyzed by the finite element method, in which the mechanical model was employed as the constitutive relation. The fracture behavior from a crack tip in WC-Co hardmetals was discussed based on the analytical results.

烧结材料宏观上是均匀的，但微观上是不均匀的。因此，烧结材料的变形和断裂行为受非均匀性控制。本文对WC-Co硬质合金的变形和断裂行为进行了试验研究，并提出了一个估算两相烧结材料变形的力学模型。通过拉伸试验、压缩试验和疲劳试验，研究了WC-Co硬质合金的断裂机理，并利用扫描电镜和能谱仪对断口进行了分析。在此基础上，建立了两相烧结材料的力学模型，该模型不仅能预测材料的整体弹性模量和整体瞬时弹塑性模量，而且能预测各相的微观应力/应变。将该模型应用于不同Co体积分数的WC-Co硬质合金的变形行为的估算，得到了WC-Co硬质合金在单轴拉伸试验下的整体弹性模量和整体应力-应变关系，与试验结果吻合较好。从微观应力/应变的角度解释了WC-Co硬质合金抗弯强度随Co体积分数的变化规律。以力学模型为本构关系，采用有限元法分析了WC-Co硬质合金裂纹尖端的宏观应力应变场和细观应力应变场。根据分析结果，讨论了WC-Co硬质合金裂纹尖端的断裂行为。