激光功率对高熵合金/316L不锈钢材料组织及力学性能的影响

Effect of laser power on microstructure and mechanical properties of high entropy alloy/316L stainless steel materials

选区激光熔化(SLM)制备的金属基复合材料具有结构灵活、成分可控等诸多优势。以316L不锈钢为基体材料,Al_(0.5)CoCrFeNiTi_(0.5)高熵合金(HEA)粉末为颗粒增强体,研究激光功率对Al_(0.5)CoCrFeNiTi_(0.5)/316L材料微观组织、微纳力学和宏观力学性能在SLM打印过程中的影响。结果表明,随着激光打印功率从175 W增加到190W,Al_(0.5)CoCrFeNiTi_(0.5)/316L材料内部的成形质量降低,内部产生微裂纹等缺陷,同时未见高熵合金的原始球形颗粒存在,材料内部元素分布均匀,Al_(0.5)CoCrFeNiTi_(0.5)颗粒的添加使熔池的流动性降低,打印位置重熔区晶粒呈现出等轴晶分布。随着激光功率的增加,重熔区和非重熔区的硬度增加,弹性回复率整体呈增加趋势,抗拉强度和延伸率也随着激光功率的增加而降低,复合材料的抗拉强度最高可达1 136 MPa,在316L基体内部加入Al_(0.5)CoCrFeNiTi_(0.5)颗粒后,其内部的强化机理主要是固溶强化,断裂形式表现为韧性断裂。

Selective laser additive manufacturing(SLM)fabricated metal matrix composites have many advantages such as flexible structure and controllable composition.In this paper,316L stainless steel was used as the matrix material and Al_(0.5)CoCrFeNiTi_(0.5)high entropy alloy(HEA)powder was used as the particle reinforcement to study the effect of laser power on the microstructure,micro-nano mechanical and macro-mechanical properties of Al_(0.5)CoCrFeNiTi_(0.5)/316L composites during SLM printing.The results show that with the increase of laser power,the forming quality of the composite decreases and the microcracks occur in the composite.The original spherical particles of high entropy alloy do not exist,the elements in the composite are evenly distributed,the fluidity of the adding pool of Al_(0.5)CoCrFeNiTi_(0.5)particles decreases,and the remelted zone presents equiaxed crystal distribution.With the increase of laser power,the hardness of remelted zone and non-remelted zone increases,and the elastic recovery rate decreases as a whole.The tensile strength and elongation also decrease with the increase of laser power,and the tensile strength is up to 1136 MPa.The internal strengthening mechanism of Al_(0.5)CoCrFeNiTi_(0.5)particles is mainly attributed to solid solution strengthening and the fracture form is ductile fracture.