退火及深冷处理对SLM成形ZL114A合金组织及性能的影响

以选区激光烧结(SLM)成形ZL114A合金为研究对象,进行了SLM成形ZL114A合金的退火和深冷处理工艺试验,主要研究了退火温度和深冷保温时间对SLM成形ZL114A合金微观组织和力学性能的影响。结果表明,230℃×2h退火处理后,SLM成形ZL114A合金的伸长率提高了18.0%,抗拉强度下降了2.9%;300℃×2h退火处理导致合金的抗拉强度和伸长率下降了28.2%和22.3%;合金退火态的微观组织表现为α-Al与Si相交界处存在大量的孔洞。而深冷处理(-196℃)对SLM成形ZL114A合金的力学性能有明显改善,其中深冷保温36h对力学性能提升效果最佳,相较沉积态,其抗拉强度提高了18.9%,伸长率提高了23.0%;其深冷态的共晶Si在基体中分散更均匀,并转为棒状结构,使合金的塑性得到明显提高。

Effects of Annealing and Cryogenic Treatment on Microstructure and Properties of ZL114A Alloy Formed by SLM Technology

The effects of annealing temperature and cryogenic holding time on the microstructure and mechanical properties of SLM-formed ZL114 Aalloy were investigated by OM,SEM,EDS and tensile testing.The results demonstrate that after 230℃×2 hannealing treatment,the elongation of the alloy is increased by 18.04%,while the tensile strength is decreased by 2.94%,and annealing treatment at 300℃×2 hresults in a decrease of28.19%in tensile strength and 4.55%in elongation of the alloy.The annealed microstructure of the alloy presents a large number of pores at the junction ofα-Al and Si phase.Cryogenic treatment(-196℃)can significantly improve the mechanical properties of SLM-formed ZL114 Aalloy,where the holding time of 36 hhas the best effect.Compared with the those of deposited state ones,its tensile strength and elongation are increased by 18.99%and23.03%,respectively.The cryogenic eutectic Si is more evenly dispersed in the matrix and transformed into a rodlike structure,which significantly enhances the plasticity of the alloy.