低活化Fe36.41Cr28.06V35.53单相中熵合金的组织演化及性能研究

Microstructures Evolution and Mechanical Properties of Low-Activation Single-Phase Fe36.41Cr28.06V35.53 Medium-Entropy Alloys

摘要:

材料是核聚变堆应用的瓶颈问题之一。本文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Fe36.41Cr28.06V35.53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Fe36.41Cr28.06V35.53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。Fe36.41Cr28.06V35.53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Fe36.41Cr28.06V35.53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。

Abstract:

Materials are the bottleneck of the fusion reactor application. 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 Fe36.41Cr28.06V35.53 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 Fe36.41Cr28.06V35.53 alloy are 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 Fe36.41Cr28.06V35.53 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 Fe36.41Cr28.06V35.53 alloy were characterized in details, and the mechanism of the excellent properties for the alloy was also explained.