The effect of diamond surface pretreatment and content on the microstructure and mechanical properties of NiAl/Fe–x diamond (x = 0, 5, 10, 15, and 20 wt.%) alloys was investigated after mechanical alloying with subsequent hot-pressing sintering. The results showed that after the surface pretreatment, a complete transition layer containing W existed on the outer surface of the diamond grains, which improved the interfacial bonding strength of the diamond grains and NiAl/Fe matrix to an excellent level. As the diamond content increased, the compressive strength of the NiAl/Fe-based alloys declined, but the alloy with 10 wt.% diamond had a higher value than that of the other NiAl/Fe-based alloys. Short cracks and transgranular fracture were observed in the fracture surface of all materials. For the material with 20 wt.% diamond, intergranular fracture was obvious, and many diamond particles appeared along the fracture direction, which caused the compressive strength to be the lowest of the samples considered in this study. After the addition of diamond, the oxidation resistance of NiAl/Fe-based alloys decreased due to a loose oxidation layer and diamond graphitization. The thermal conductivity of the alloy first increased and then decreased with increasing diamond content. A NiAl/Fe-based alloy with 15 wt.% diamond demonstrated the maximum thermal conductivity of 53.2 W/(m·k) at 600°C among the samples in this study.

中文翻译：

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金刚石表面预处理和含量对 NiAl/Fe 基合金组织和机械氧化行为的影响

在机械合金化和随后的热压烧结后，研究了金刚石表面预处理和含量对 NiAl/Fe-x 金刚石（x = 0、5、10、15 和 20 wt.%）合金的微观结构和机械性能的影响. 结果表明，经过表面预处理后，金刚石晶粒外表面存在完整的含W过渡层，使金刚石晶粒与NiAl/Fe基体的界面结合强度提高到了极好的水平。随着金刚石含量的增加，NiAl/Fe 基合金的抗压强度下降，但含 10 wt.% 金刚石的合金的抗压强度高于其他 NiAl/Fe 基合金。所有材料的断口均观察到短裂纹和穿晶断裂。对于含 20 wt.% 金刚石的材料，晶间断裂明显，沿断裂方向出现许多金刚石颗粒，这导致抗压强度是本研究考虑的样品中最低的。加入金刚石后，NiAl/Fe基合金由于氧化层松散和金刚石石墨化，抗氧化性能下降。合金的热导率随着金刚石含量的增加先增加后降低。在本研究中的样品中，含有 15 wt.% 金刚石的 NiAl/Fe 基合金在 600°C 下的最大热导率为 53.2 W/(m·k)。由于松散的氧化层和金刚石石墨化，NiAl/Fe 基合金的抗氧化性下降。合金的热导率随着金刚石含量的增加先增加后降低。在本研究中的样品中，含有 15 wt.% 金刚石的 NiAl/Fe 基合金在 600°C 下的最大热导率为 53.2 W/(m·k)。由于松散的氧化层和金刚石石墨化，NiAl/Fe 基合金的抗氧化性下降。合金的热导率随着金刚石含量的增加先增加后降低。在本研究中的样品中，含有 15 wt.% 金刚石的 NiAl/Fe 基合金在 600°C 下的最大热导率为 53.2 W/(m·k)。