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硬质合金是由难熔金属化合物和粘结相通过粉末冶金工艺制成的材料,它具有硬度高、耐磨、强度和韧性好、耐热、耐腐蚀等一系列优良性能。介绍了包含C-Co-Cr-W-Ta-Ti-Nb-N等元素的硬质合金热力学和动力学数据库。简述了热力学数据库中的热力学模型和优化计算,并以C-Cr-Ta三元系为例介绍了热力学优化计算的方法和步骤。所建立的硬质合金动力学数据库包含液相和fcc相不同元素的原子迁移参数。利用修正的Sutherland方程对液相的原子迁移参数进行了评估,而fcc相原子迁移参数是基于对实验测定数据和文献数据的评估获得的。利用建立的硬质合金热力学和动力学数据库,可以计算多元系的相平衡、获取不同相的热力学性质和溶解度信息、模拟合金中元素和相的分布等。该数据库可用于设计合金成分和烧结温度、预测元素含量及烧结气氛等对梯度硬质合金形成的影响、优化合金烧结工艺等。最后指出相图热力学和扩散动力学数据库及热物性数据库结合相场、有限元方法,定量描述硬质合金结构-性能的关系是今后的发展趋势。
Carbide is made of refractory metal compounds and binder phase through the powder metallurgy process made of materials, it has high hardness, wear resistance, strength and toughness, heat resistance, corrosion resistance and a series of excellent performance. The cemented carbide thermodynamics and kinetics database containing C-Co-Cr-W-Ta-Ti-Nb-N and other elements is introduced. The thermodynamic model and optimization calculation in the thermodynamic database are briefly introduced. The C-Cr-Ta ternary system is taken as an example to introduce the method and procedure of thermodynamic optimization calculation. The established cemented carbide kinetic database contains atomic mobility parameters for different elements in the liquid and fcc phases. The modified Sutherland equation was used to estimate the atomic migration parameters of the liquid phase, while the fcc phase atomic migration parameters were obtained based on the experimental determination data and literature data. Based on the developed database of thermodynamics and dynamics of cemented carbide, the phase equilibrium of the multivariate system can be calculated, and the thermodynamic properties and solubility information of different phases can be obtained to simulate the distribution of elements and phases in the alloy. The database can be used to design the alloy composition and sintering temperature, predict the element content and sintering atmosphere on the formation of gradient cemented carbide, and optimize the alloy sintering process. Finally, it is pointed out that the relationship between phase diagram, thermodynamic and diffusion kinetics database and thermophysical database combined with phase field and finite element method to quantitatively describe the structure-property relationship of cemented carbide is the development trend in the future.