烧结温度对WC-Al0.5CoCrFeNiTi0.5硬质合金微观组织及性能的影响

Effect of sintering temperature on microstructure and properties of WC-Al0.5CoCrFeNiTi0.5 cemented carbides

关键词:  硬质合金  高熵合金粘结相  真空热压烧结  微观组织  力学性能

Key words:  cemented carbide  high-entropy alloy binder  hot pressing sintering  microstructure  mechanical properties

摘要:

为开展烧结温度对以高熵合金(HEA)为粘结相的WC硬质合金组织及性能的影响研究,本文以Al0.5CoCrFeNiTi0.5高熵合金为粘结相,采用高能球磨和真空热压烧结技术制备了WC-Al0.5CoCrFeNiTi0.5硬质合金,利用正交试验设计,采用SEM、XRD和显微硬度计等方法,研究了烧结参数对WC-Al0.5CoCrFeNiTi0.5硬质合金微观组织和性能的影响。研究表明,烧结温度对WC-Al0.5CoCrFeNiTi0.5硬质合金的力学性能有显著影响。烧结温度的升高有助于改善合金微观组织均匀性,从而提高合金的相对密度。同时,WC晶粒形貌逐渐趋于平衡状态,且WC晶粒尺寸增大,合金相对密度提高。当烧结温度从1 200 ℃升高至1 300 ℃时,合金硬度逐渐降低,断裂韧性呈现出先增加后降低的趋势。在烧结温度为1 250 ℃时,WC-20 wt.%HEA硬质合金的相对密度为98.85%,硬度和断裂韧性分别为2 028HV和9.01 MPa·m^{1/2,表现出优良的综合力学性能。在本文的实验条件下,WC晶粒尺寸是影响WC-Al0.5CoCrFeNiTi0.5}硬质合金相对密度和硬度的关键因素,WC晶粒形貌是影响断裂韧性的主要因素。

Abstract:

To investigate the impact of sintering temperature on the microstructure and properties of WC-based cemented carbide with high entropy alloy (HEA) binder phase, WC-Al0.5CoCrFeNiTi0.5 cemented carbides were prepared by high-energy ball milling and vacuum hot pressing sintering techniques in this study. Employing orthogonal experimental design, the influence of sintering temperature on the microstructure and properties of WC-Al0.5CoCrFeNiTi0.5 cemented carbides was stdied using SEM, XRD and microhardness tester methods.The results show that sintering temperature significantly affects the mechanical properties of the WC-Al0.5CoCrFeNiTi0.5 cemented carbides. Increasing the sintering temperature helps improve the homogeneity of the WC-Al0.5CoCrFeNiTi0.5 cemented carbides, thereby enhancing the relative density of the cemented carbide.At the same time, the morphology of WC grains progressively approaches an equilibrium state, and the size of WC grains increases, enhancing the relative density of the WC-Al0.5CoCrFeNiTi0.5 cemented carbides. The fracture toughness exhibits a trend of initially increasing and then decreasing as the sintering temperature elevated from 1 200 ℃ to 1 300 ℃, while the hardness gradually decreases.At 1 250 ℃, the WC-Al0.5CoCrFeNiTi0.5 cemented carbide exhibited excellent comprehensive mechanical properties, with a relative density of 98.85%, hardness and fracture toughness values of 2 028HV and 9.01 MPa·m^1/2, respectively. Under the experimental conditions of this study, the size of WC grains is identified as a critical factor affecting the relative density and hardness of the WC-Al0.5CoCrFeNiTi0.5 cemented carbides, while the morphology of WC grains is the primary factor influencing the fracture toughness.