低活化Fe_(36.41)Cr_(28.06)V_(35.53)单相中熵合金的成分设计、组织演化及性能研究

Composition Design, Microstructures Evolution and Properties of Low-Activation Single-Phase Fe_(36.41)Cr_(28.06)V_(35.53) Medium-Entropy Alloys

根据核聚变堆领域的要求使用低活化材料以及考虑到未来工程应用需要降低成本,选用低活化、低成本的Fe、Cr、V元素,依据最小吉布斯自由能准则设计出非等原子比Fe_(36.41)Cr_(28.06)V_(35.53)单相中熵合金。采用真空熔炼的方法制备出该合金,并对其进行适当的热机处理。发现非等比Fe_(36.41)Cr_(28.06)V_(35.53)合金在不同热机处理过程中没有发生相变,均为单相bcc固溶体,说明该合金相结构非常稳定。同时也与依据最小吉布斯自由能准则设计的结果吻合得非常好。Fe_(36.41)Cr_(28.06)V_(35.53)合金的硬度高于传统耐热合金,在不同热机加工状态下合金的压缩塑性均大于50%,实现了强度和塑性的良好配合。在压缩变形过程中,由于偏析元素与位错的相互作用,合金的压缩应力-应变曲线出现锯齿流变行为。对Fe_(36.41)Cr_(28.06)V_(35.53)合金进行了详细的微观组织表征,解释了该合金性能优异的微观机制。

According to the requirements of low activation materials and reducing cost, Fe, Cr and V elements are selected to design a single-phase medium entropy alloy with non-equal atomic ratio of Fe_(36.41)Cr_(28.06)V_(35.53)based on minimizing Gibbs free energy. The alloys were synthesized by vacuum melting method followed by hot-rolling and heat treatments. It is found that Fe_(36.41)Cr_(28.06)V_(35.53)alloy is single-phase bcc solid solution in different treatment states. No any phase transformation is detected. It reveals that the phase structure of the alloy is quite stable, which is in good agreement with the design results. The hardness of the Fe_(36.41)Cr_(28.06)V_(35.53)alloy is higher than that of the traditional heat-resistant alloys, and the compressive plasticity of the alloys in different treatment states is more than 50%, which achieves a good match of strength and plasticity. Due to the interaction between segregation elements and dislocations, the compressive stress-strain curve of the alloy exhibits serrated flow behavior during the compression deformation process. The microstructures of the Fe_(36.41)Cr_(28.06)V_(35.53)alloy were characterized in details, and the mechanism of the excellent properties for the alloy was also explained.