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配料及制备工艺对TZC钼合金显微组织的影响

Influence of ingredient and preparation process on the microstructure of TZC molybdenum alloys

  • 摘要: 采用TiH2/ZrH2和TiC/ZrC两种掺杂方式分别在不同烧结和热压工艺下制备了TZC钼合金。通过光学金相观察、扫描电子显微分析、物相分析等方法,研究了处理工艺对合金微观组织和成分的影响。结果表明,两种掺杂方式得到的TZC钼合金物相构成基本相同;烧结后合金密度由9.21 g·cm−3(添加TiH2/ZrH2)提高到9.68 g·cm−3(添加TiC/ZrC),合金硬度由HV 210提高到HV 245;热压后合金相对密度和硬度明显提高,晶粒也由烧结态的双峰型分布转变为单峰型分布。研究发现,在高温烧结过程中,两种添加物的构成都发生了转变,其反应扩散过程决定了其微观结构,从而决定了其密度和硬度的变化。添加TiH2/ZrH2的TZC钼合金经热压后的微观组织会形成不同的特征区域;添加TiC/ZrC后,通过直接热压成形可获得晶粒细小、相对密度及硬度优良的TZC钼合金。

     

    Abstract: Different sintering and hot-pressing processes were employed to prepare the TZC alloys doped by TiH2/ZrH2 and TiC/ZrC, respectively. The microstructure evolution and composition distribution of the alloys under the different processing conditions were studied by optical metallographic observation, scanning electron microscopy, and phase analysis. The results show that the phase constituents of these two doping are basically the same. Comparison with that of the TZC alloys doped by TiH2/ZrH2, the density of the TZC alloys doped by TiC/ZrC after sintering increases from 9.21 g·cm−3 to 9.68 g·cm−3, and the hardness increases from HV 210 to HV 245, respectively. Hot pressing after sintering significantly increases the density and hardness of the alloys, and the grain distribution changes from the bimodal distribution in the sintered state to the unimodal distribution. It is found that the phase structures of these two doping undergo transformation during the high-temperature sintering, which determines the reaction diffusion process and thereby affects the density and hardness. The TZC alloys doped by TiH2/ZrH2 form the different characteristic regions in the microstructure after hot pressing, and the TZC alloys doped by TiC/ZrC with fine grain, high relative density, and high hardness can be directly obtained by hot-pressing.

     

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