The materials, primarily utilized in the manufacturing process, significantly impact the microstructure and mechanical properties of W-HfC alloys. In this study, different initial composition, such as HfH2/WC, HfH2/C and HfC, were respectively mixed into W powders, three categories of W-HfC alloys (abbreviated as WHC1, WHC2 and WHC3 successively) were fabricated by in-situ reaction sintering methods. The microstructure and mechanical properties of three alloys were investigated comparatively by using X-ray diffraction, electron microscopy and high temperature tensile tests. The results revealed that WHC2 alloy presents an exceptional ductile-brittle transition temperature of ∼300 °C and the best comprehensive performance. Tensile testing at 300 °C indicates that WHC2 alloy exhibits a complete plastic fracture curve with a tensile strength of 400 MPa and a residual deformation of 9 %, as well as the plasticity enhancement. It is mainly attributable to the dispersion strengthening effect of second phase particles at grain boundaries and within W-matrix grains. Furthermore, the excellent overall performance of the WHC2 alloy demonstrates that the in-situ reaction can significantly reduce sintering difficulties, while the resultant second phase particles provide considerable advantages in improving the properties of W-based alloys. These findings provide valuable insights into the synthesis process and mechanical performance of W-HfC alloys, enabling advancements in their application in high-temperature environments.

中文翻译：

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无压烧结原位制备 W-HfC 合金的微观组织和力学性能


这些材料主要用于制造过程，对 W-HfC 合金的微观结构和机械性能产生重大影响。本研究将 HfH2/WC、HfH2/C 和 HfC 等不同初始成分分别混合到 W 粉末中，通过原位反应烧结方法制备了三类 W-HfC 合金（依次缩写为 WHC1、WHC2 和 WHC3）。采用 X 射线衍射、电子显微镜和高温拉伸试验对 3 种合金的微观组织和力学性能进行了比较研究。结果表明，WHC2 合金表现出优异的 ∼300 °C 韧性脆性转变温度和最佳的综合性能。300 °C 的拉伸试验表明，WHC2 合金表现出完整的塑性断裂曲线，拉伸强度为 400 MPa，残余变形为 9 %，塑性增强。这主要归因于第二相颗粒在晶界和 W 基体晶粒内的分散增强效应。此外，WHC2 合金的优异整体性能表明，原位反应可以显著降低烧结难度，而所得的第二相颗粒在改善 W 基合金的性能方面具有相当大的优势。这些发现为 W-HfC 合金的合成过程和机械性能提供了有价值的见解，使其在高温环境中的应用取得了进展。