Fe_(60)Cr_(18)Cu_(3)(MnCoNiMoAlTi)_(19)中熵合金时效硬化与耐蚀性能

Ageing hardening and corrosion resistance of Fe_(60)Cr_(18)Cu_(3)(MnCoNiMoAlTi)_(19) medium-entropy alloy

采用真空电弧炉熔炼制备Fe_(60)Cr_(18)Cu_(3)(MnCoNiMoAlTi)_(19)中熵合金,研究了合金的时效硬化机理和耐腐蚀性能。结果表明,中熵效应使合金凝固组织具有简单的BCC固溶体结构。HRTEM研究发现,超饱和固溶体基体高晶格畸变有利于合金时效后纳米有序B2共格相大量弥散析出,最高时效硬度达到621HV_(0.5)。特别是抗热硫酸腐蚀和NaCl溶液点蚀性能与相同Cr、Ni含量的时效硬化不锈钢17-4PH相比均获得了大幅提升,表现为更宽、更稳定的阳极钝化区和显著较低的腐蚀溶解速度。XPS分析结果表明,高含量Cr_(hy)^(3+)、Cr_(ox)^(3+)、Cu_(ox)^(+)、Ti_(ox)^(4+)、Al_(ox)^(3+)和Mo_(ox)^(6+)耐蚀元素离子组成的多元钝化膜是其抑制Cl-点蚀坑形核和扩展的重要原因。

Fe_(60)Cr_(18)Cu_(3)(MnCoNiMoAlTi)_(19) medium-entropy stainless alloy(MEA)was prepared by vacuum arc furnace melting.The ageing hardening mechanism and corrosion resistance of alloy were studied.The results show that the MEA has simple BCC solid solution phase after solidification,due to the influence of medium-entropy effect.HRTEM results show that the high level of lattice distortion in the supersaturated BCC solid solution matrix leads to a high amount of nanometer-sized ordered B2 coherent precipitates after ageing treatment,and the maximum hardness of MESS after ageing reaches 621HV0.5.The resistance to corrosion in hot sulfuric acid and to pitting in the NaCl solution are both greatly improved compared with the conventional 17-4PH steel,as evidenced by more stable anodic passivation zone and significantly reduced corrosion dissolution rate in the MEA.XPS analyses results show that the multi-component passive film,which composes of high contents of anti-corrosion elements including Cr_(hy)^(3+)、Cr_(ox)^(3+)、Cu_(ox)^(+)、Ti_(ox)^(4+)、Al_(ox)^(3+)and Mo_(ox)^(6+),is the main reason for the excellent pitting resistance and the reduced growth of pitting pit in the NaCl solution.