【摘要】 打印态CoCrFeMnNi高熵合金具有分级微观结构,随着退火温度从700℃提升至1100℃,高熵合金的微观组织发生了显著变化。打印态由熔池、柱状晶和胞状亚晶组成,退火后熔池边界和胞状亚晶逐步消失,同时晶粒逐渐增大。高熵合金在酸性溶液中的腐蚀以晶间腐蚀为主,且腐蚀电流密度随着退火温度的升高逐渐减小。相比于打印态试样,1100℃退火试样的腐蚀电流密度降低了58%,腐蚀电位提升了61%。打印态试样和1100℃退火试样钝化膜中耐蚀元素在钝化膜中的占比分别为55.4%和63.2%,Cr本征氧化层厚度则分别增加至2.7 nm和3.1 nm。由于化学活性更高的熔池边界和胞状亚晶的消失及钝化膜抵抗酸蚀的能力增强,1100℃退火试样表现出最佳的耐蚀性能。更多还原

【Abstract】 The as-printed CoCrFeMnNi high-entropy alloy(HEA) possesses a hierarchical microstructure,which undergoes significant transformation with the increase of annealing temperature from 700℃ to1100℃.The as-printed state consists of melt pools,columnar grains,and cellular sub-grain structure.The melt pool boundaries and cellular sub-grain structure gradually disappear after annealing,while the grain size gradually increases.The corrosion of HE As in acidic solutions is mainly intergranular corrosion,and the corrosion current density gradually decreases with the increase of annealing temperature.Compared with the as-printed sample,the corrosion current density of the 1100℃ annealed sample decreased by 58%,and the corrosion potential increased by 61%.The proportion of corrosion-resistant elements in the passive film was 55.4% and 63.2% for the as-printed and 1100℃-annealed samples,respectively,and the intrinsic Cr oxide layer thickness increased to 2.7 nm and 3.1 nm.The disappearance of the highly reactive melt pool boundaries and cellular sub-grains,in conjunction with enhanced acid resistance of the passive film,collectively contributes to the superior corrosion resistance exhibited by the sample annealed at 1100℃.更多还原