Co-Ni-Al复合粘结硬质合金的相图热力学及微结构控制机理研究

Because Co is a scarce strategic resource, choosing a composite binder of Co and Ni-Al intermetallic compound，which is of good resistance to oxidation and corrosion, has gradually become an important research direction in the field of binder modification of cemented carbide. The performance of materials is largely dependent on their microstructure. Knowledge of the thermodynamic data of the Co-Ni-Al composite bonded cemented carbide is the key to the process parameter optimization and alloy design. Choosing W-C-Co-Ni-Al multicomponent system as the target, the present proposal is devoted to: 1) develop a scientific method of combining key experiment, CALPHAD approach and first-principles calculation to establish an accurate thermodynamic description of this system, 2) design model alloys under the background of industrial application based on thermodynamic simulations in order to obtain the phase equilibrium data which could not be accurately determined in traditional cemented carbides, validate and further refine the established thermodynamic description, and 3) conduct experimental characterization of microstructure with the aid of thermodynamic simulations to study the influence of various process parameters on the microstructure, and then clarify the control mechanism of microstructure of Co-Ni-Al composite bonded cemented carbides. The completion of this project is expected to lay a basis of theoretical importance for the design of Co-Ni-Al composite bonded cemented carbides, and provide a scientific method for the design of alloy composition and the control of microstructure for other cemented carbides.

因为Co是稀缺的战略资源，所以将具有优异抗氧化和耐腐蚀性能的Ni-Al金属间化合物与 Co复合形成粘结相逐渐成为了硬质合金粘结相改性的一个重要研究方向。材料的性能主要取决于组织结构，掌握Co-Ni-Al复合粘结硬质合金的热力学信息是工艺参数优化和合金设计的关键。本项目拟以W-C-Co-Ni-Al五元系为研究对象开展如下研究：1）发展耦合关键实验、相图计算和第一性原理计算的科学方法，获得该体系的热力学描述；2）基于计算模拟，设计具有工业应用背景的模型合金，获得传统硬质合金中无法精确测定的相平衡信息，验证并完善所建立的热力学描述；3）基于热力学模拟开展微结构的实验表征，研究各种工艺参数对组织结构的影响，掌握Co-Ni-Al复合粘结硬质合金微结构的控制机理。本项目的完成可望为Co-Ni-Al复合粘结硬质合金的开发设计奠定理论基础，并为其它硬质合金的成分设计和微结构控制提供一种可借鉴的科学方法。

具有优异抗氧化和耐腐蚀性能的Ni-Al金属间化合物与Co复合形成粘结相逐渐成为了硬质合金粘结相改性的一个重要研究方向。掌握Co-Ni-Al复合粘结硬质合金的热力学信息是工艺参数优化和合金设计的关键。本项目以W-C-Co-Ni-Al五元硬质合金体系为研究对象，在资助期间取得了如下成果：（1）建立了W-C-Co-Ni-Al五元系硬质合金热力学数据库，并拓展加入了Mo、Ta、Ti等重要的二次碳化物金属元素；（2）基于热力学计算设计了WC-Co和WC-Ni模型合金，并采用EPMA精确测定了粘结相的组分，拓展了微结构的精准表征手段；（3）研究了复合粘结相的成分、WC晶粒度和粒度分布以及长时间低温时效等对Co-Ni-Al复合粘结相中析出纳米有序相微观组织结构的影响；（4）建立了耦合热力学数据库、/´界面能以及共格析出弹性能的多相场模型，利用相场方法研究了各种工艺参数对WC-Co-Ni3Al硬质合金复合粘结相中纳米有序析出相微观组织结构演变的影响。在CALPHAD、J. Alloy Compd.、Cer. Inter.等国际知名刊物发表SCI收录论文23篇、EI收录会议论文2篇，其中标注本项目资助号13篇。培养博士研究生1名、硕士研究生4名。