梯度硬质合金梯度层形成的计算机模拟及验证

COMPUTER SIMULATIONS AND VERIFICATION OF GRADIENT ZONE FORMATION IN CEMENTED CARBIDES

建立了多组元梯度硬质合金W-C-Co-Ti-Ta-Nb-N体系的热力学和扩散动力学数据库,采用Thermo-Calc相图热力学计算软件描述了梯度烧结过程中出现的各相及其成分,并采用DICTRA扩散动力学软件对WC-Ti(C,N)-Co,WC-Ti(C,N)-TaC-Co和WC-Ti(C,N)-NbC-Co合金梯度层的各相体积分数及各组元成分随距离的分布进行了计算机模拟,模拟结果与实验结果吻合良好.在热力学和扩散动力学数据库基础上制备了WC-(Ti,W)C-Ti(C,N)-(Ta,Nb)C-Co合金,采用SEM观察梯度层的显微结构,利用EDS分析合金组元分布,并对合金梯度层的形成进行了计算模拟,模拟结果与实验结果吻合良好.

The thermodynamic and kinetic databases for multi-component W C-Co-Ti-Ta- Nb N cemented carbides were established. The Thermo Calc software was used to describe the phase composition of alloys during gradient sintering. Based on the established thermodynamic and kinetic databases, the volume fractions of different phases and elemental concentration profiles in the WC- Ti（C, N）-Co, WC Ti（C, N）-TaC-Co and WC-Ti（C, N） NbC Co alloys were simulated by means of DICTRA software. The simulated results are in good agreement with the experimental data. In order to verify the reliability of the thermodynamic and kinetic databases, a gradiently sintered WC-Ti（C, N） TaC-NbC-Co cemented carbide has been prepared. SEM and EDS were employed to examinate the microstructure and composition in the gradient zone. The gradient zone formation of the WC Ti（C, N） TaC-NbC-Co cemented carbides was then simulated by DICTRA, and the simulation results show a good agreement with the experimental results.