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烧结工艺对钨铼合金显微组织及力学性能的影响

Effect of sintering process on microstructure and mechanical properties of W–Re alloys

  • 摘要: 采用粉末冶金工艺制备W–5.0Re–0.5HfC合金,系统研究了氢气、真空及真空+氢气复合烧结三种工艺对合金显微组织与室温力学性能的影响。结果表明:经真空+氢气烧结所得坯料表现出最优综合性能,其平均晶粒尺寸(32.6 μm)与密度(17.75 g·cm−3)介于氢气烧结(49.2 μm,18.42 g·cm−3)和真空预烧(12.4 μm,16.60 g·cm−3)之间,并表现出最佳的锻造工艺适应性。经高温变形处理后,真空+氢气烧结试样的室温抗拉强度(1425.11 MPa)略低于氢气烧结试样(1513.20 MPa),但其延伸率显著提升至16.2%。氢气烧结试样中第二相以纳米尺度碳化铪(HfC)为主,通过弥散强化机制显著提升材料强度;真空+氢气烧结试样中形成与基体结合紧密的氧化铪(HfO2)颗粒,在有效细化晶粒的同时协调位错运动,从而显著改善塑性变形能力,实现了强度与塑性最优匹配。

     

    Abstract: The W–5.0Re–0.5HfC alloys were prepared by powder metallurgy, and the effects of three sintering processes on the microstructure and room-temperature mechanical properties of the alloys were systematically investigated, including hydrogen, vacuum, and vacuum+hydrogen sintering. The results indicate that the vacuum+hydrogen sintered billets exhibit the optimal comprehensive performance, with the average grain size (32.6 μm) and density (17.75 g·cm−3) intermediate between those of the hydrogen sintered (49.2 μm, 18.42 g·cm−3) and vacuum sintered (12.4 μm, 16.60 g·cm−3) billets, along with the optimal forging process adaptability. After the high-temperature deformation treatment, the room-temperature tensile strength of the vacuum+hydrogen sintered specimens (1425.11 MPa) is slightly lower than that of the hydrogen sintered specimens (1513.20 MPa), but the elongation significantly increases to 16.2%. The higher strength of the hydrogen sintered samples is attributed to the predominant presence of nano-sized hafnium carbide (HfC) particles through the dispersion strengthening mechanism. In contrast, the vacuum+hydrogen sintered specimens contain the hafnium oxide (HfO2) particles, tightly bonding to the matrix, effectively refining the grains, and coordinating the dislocation motion, which markedly improve the plastic deformation capability and result in the optimal balance between strength and ductility.

     

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