选区激光熔化FeCoNiCr系高熵合金微观组织的实验研究

Experimental Study on the Microstructure of FeCoNiCr High-Entropy Alloys by Selective Laser Melting

介绍了关于选区激光熔化的热分析理论,利用选区激光熔化技术制备FeCoNiCrAl_(0.5)和FeCoNiCrAl_(0.8)高熵合金试件.利用超景深显微镜对试件微观组织进行观测,分析了粉末粒径、元素含量,以及工艺参数等因素对选区激光熔化高熵合金的微观组织的影响.结果表明,随着激光功率增大,试件顶部等轴晶的占比越来越少,尺寸越来越细小,试件底部组织中枝晶的占比逐渐增多,尺寸不断增大;随着扫描速度增大,高熵合金试件底部组织中枝晶尺寸逐渐减小、宽度变窄;搭接率对高熵合金试件微观组织影响较小;制得的高熵合金试件存在着裂纹、凹陷及气孔等缺陷.

The thermal analysis theory of selective laser melting was introduced,and FeCoNiCrAl _(0.5) and FeCoNiCrAl_( 0.8) high-entropy alloys were prepared by selective laser melting.The effects of powder particle size,element content and process parameters on the microstructure of high-entropy alloys by selective laser melting were analyzed.The results showed that with the increase of laser power,the proportion of equiaxed crystals at the top of the specimen becomes smaller,while the proportion of dendrites in the bottom of the specimen becomes larger and larger.With the increase of scanning speed,the size and width of dendrite in the bottom of high-entropy alloy specimens decrease gradually.The effect of lap ratio on the microstructure of high-entropy alloys is small.It was found that the high-entropy alloy specimens have some defects such as cracks,dents and pores.