Improve the microstructure and properties of Al0.5CoCrFeNi compositionally complex alloy fabricated by selective laser melting with electropulsing treatment

In order to improve the microstructure of the Al0.5CoCrFeNi compositionally complex alloy (CCA) prepared by selective laser melting (SLM), the electropulsing treatment (EPT) has been used as a post processing in this study. The strengthening and softening mechanism was analyzed by comparing the microstructure of SLM-Al0.5CoCrFeNi CCAs under different EPT parameters. At a 10 s power on time, the substructure size of CCA decreases continuously with increasing voltage. Under 90V/10s EPT, the yield strength increases from 658 +/- 10 MPa in the printed state to 748 +/- 17 MPa, and the microhardness increases from 265.1 +/- 5.6 HV0.1 to 318.9 +/- 5.0 HV0.1. At 90V/20s EPT, the cellular substructure disappears, and a large number of uniformly distribute BCC phases precipitates inside the FCC matrix. At 90V/30s EPT, recrystallization occurs and the BCC phase coarsen. Dislocation network is the main factor that affects the strength of SLM-CCA. EPT can change the dislocation network structure to enhance the strength of SLM-CCA. Simultaneously, the EPT effectively promotes the transition from FCC phase to BCC phase in a short time. Joule heat and electronic wind force are the main reasons for changing structure and properties of SLM-Al0.5CoCrFeNi CCA. This work provides a post-processing method named as EPT to effectively control the microstructure in additive manufacturing CCA products.