Mn13钢基材表面真空钎焊Al1.2CoCrFeNi2.1高熵合金的微观组织与性能

Microstructure and Properties of Vacuum Brazed Al1.2CoCrFeNi2.1 High-Entropy Alloy onto the Surface of Mn13 Steel Substrate

摘要:

针对传统钢材Mn13钢等在大规模应用中暴露出的低应力耐磨性差、低温脆性和易生锈等问题，采用在Mn13钢表面焊接具有高强度、良好的延展性和耐蚀性的Al_1.2CoCrFeNi_2.1近共晶高熵合金来改善其表面性能。采用BNi2钎料通过真空钎焊的方式在Mn13钢表面钎焊Al_1.2CoCrFeNi_2.1高熵合金，并对高熵合金母材和钎焊接头的微观组织与力学性能进行了探究，同时研究了真空钎焊温度对钎焊层微观组织和力学性能的影响。实验结果表明：母材Al_1.2CoCrFeNi_2.1高熵合金的显微组织由FCC相和有序B2相组成，钎焊后合金组织中B2相体积分数增加，显微维氏硬度从（436±15.7）HV升至（472±7.1）HV；钎焊接头的微观组织主要为Ni基的固溶体相和硼化物相，焊缝中心主要以CrB为主，扩散区则以B元素与母材元素形成的硼化物为主；钎焊温度过低或者过高会在焊缝形成气孔及硼化物，从而降低钎焊接头的剪切强度，当钎焊温度为1 050 ℃时，焊接接头的剪切强度达到最大值684.6 MPa。

Abstract:

In response to the issues of poor low-stress wear resistance， low-temperature brittleness and easy rusting exposed in large-scale applications of conventional steels such as Mn13 steel， a near-eutectic Al_1.2CoCrFeNi_2.1 high-entropy alloy was welded onto the surface of Mn13 steel to improve its surface properties. The microstructure and mechanical properties of the high-entropy alloy base material and brazed joints were studied by brazing Al_1.2CoCrFeNi_2.1 high-entropy alloy onto the surface of Mn13 steel by vacuum brazing with BNi2 brazing material. The effect of vacuum brazing temperature on the microstructure and mechanical properties of the brazed layer was investigated. The experimental results showed that the microstructure of the base material Al_1.2CoCrFeNi_2.1 high-entropy alloy consisted of FCC phase and ordered B2 phase. The volume fraction of the B2 phase increased in the alloy after brazing， and the microscopic Vickers hardness increased from （436±15.7） HV to （472±7.1） HV. The microstructure of the brazed joint was mainly Ni-based solid solution phase and boride phase. The center of the weld was dominated by CrB， and the diffusion zone was dominated by the borides formed by the B element and the base material element. Brazing temperature that is too low or too high will form pores and borides in the weld， thus reducing the shear strength of the brazed joint. Experiments showed that when the brazing temperature was 1 050 ℃， the shear strength of the welded joint reached a maximum of 684.6 MPa.