Abstract
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.
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