WC-Co硬质合金的显微结构参数

Microstructure Parameters of WC-Co Cemented Carbide

通过X射线衍射分析 (XRD) ,扫描电镜 (SEM)体视学测量和磁性与密度测试 ,并依据碳化钨(WC)基合金维氏硬度HV与γ相平均自由程λ间的Hall Petch型关系式和HV的“混合物规则”进行验证 ,探讨了两相WC Co硬质合金显微结构参数间的定量关系。结果表明 ,γ相平均自由程λ与WC晶粒邻接度CWC 间存在反向对应关系 ,与γ相体积分数fγ 和WC平均晶粒尺寸LWC 间存在正向对应关系 :λ =1 0 5× 10 - 5·(1-CWC) 3 7=8 74× 10 - 2 ·(f- 1γ - 1) - 0 79·L0 79WC ,说明fγ 和LWC对λ～CWC关系的影响处在测量误差范围内 ,因而用CWC(或λ)、fγ 和LWC中任意两个参数都能准确表征两相WC Co硬质合金的结构特征 ;合金的比矫顽磁力HSC与γ相平均自由程λ间存在定量关系 :HSC=4 0 5× 10 - 7 λ。讨论了用磁性和密度测定值无损鉴定两相WC Co硬质合金显微结构参数的可行性。

The quantitative relationships between microstructure parameters are deduced by means of XRD phase analysis, SEM stereological technique, magnetism and density testing and are verified by use of the Hall-Petch relation of Vickers hardness with the γ-phase free path λ and the mixture rule of hardness for two-phase WC-base cemented carbide. The results show that the relation of the γ-phase free path λ with the WC grain contiguity is in opposite correlation and the relation of λ with the γ-phase volume fraction fλ and the WC average grain size LWC is in positive correlation: λ = 1.05 × 10-5 (1 -CWC)3.7 = 8.74 × 10-2 (fr-1 - 1)-0.79&middotLWC0.79. It shows that the effect of fλ and LWC on the λ - (1 - CWC) relation is within the limits of test error, so the structure of two-phase WC-Co alloy can be exactly charactered by use of any two parameters among λ (or CWC), fλ and LWC. The relationship of λ with the specific coercive force HSC is HSC = 4.05 × 10-7/λ. The feasibility of predicting the microstructure parameters of two-phase WC-Co alloy by specific coercive force HSC and specific saturation magnetization, density values is discussed.