不同烧结温度对WC-10CuFeNiCrCo硬质合金微观组织结构及力学性能的影响

Effect of different sintering temperatures on microstructure and mechanical properties of WC-10CuFeNiCrCo hard alloy

  • 摘要: 采用CuFeNiCrCo高熵合金粉末为黏结剂,与WC粉末高能球磨10 h后,经放电等离子烧结制得WC-10%CuFeNiCrCo硬质合金。研究不同烧结温度(1 350、1 420 ℃及1 480 ℃)对WC-10CuFeNiCrCo硬质合金微观组织结构及力学性能的影响。研究表明:HEA黏结相合金的固相阶段快速致密化时间早于Co黏结相合金,且不同烧结温度下制备的WC-10CuFeNiCrCo硬质合金均未观察到宏观孔隙、缺碳相和游离碳的存在。随着烧结温度的升高,WC-10CuFeNiCrCo硬质合金的晶粒度呈先增加后降低的趋势,且1 480 ℃烧结合金中出现了板条状粗WC晶粒,使得WC(0001)峰强度降低且向低角度偏移。当烧结温度为1 350 ℃时,WC-10CuFeNiCrCo硬质合金的综合性能优于WC-10Co合金,其粗大WC晶粒的存在使裂纹在扩展过程中出现了裂纹偏转和裂纹桥接的现象,有效阻碍了裂纹的扩散扩展。

     

    Abstract: CuFeNiCrCo high-entropy alloy powder, as a binder, was sintered for 10 hours by high-energy ball milling with WC powder. Then, WC-10%CuFeNiCrCo hard alloys were prepared by discharge plasma sintering. The effects of different sintering temperatures (1 350℃, 1 420 ℃, and 1 480 ℃) on the microstructure and mechanical properties of WC-10CuFeNiCrCo hard alloys were studied. The results indicate that the solid-phase rapid densification time of HEA bonding phase alloys is earlier than that of Co bonding phase alloys, and no macroscopic pores, carbon-deficient phases, or free carbon are observed in WC-10CuFeNiCrCo hard alloys prepared at different sintering temperatures. With the increase of sintering temperature, the grain size of WC-10CuFeNiCrCo hard alloy increases first and then decreases. The lath-like coarse WC grains appear in the sintered alloy at 1 480 ℃, which reduces the peak strength of WC (0001) and shifts to a low angle. At a sintering temperature of 1350 ℃, the comprehensive performance of WC-10CuFeNiCrCo hard alloy is superior to that of WC-10Co alloy. The presence of coarse WC grains causes crack deflection and bridging during the crack propagation process, effectively hindering the diffusion and propagation of cracks.

     

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