Crack mitigation in additively manufactured AlCrFe2Ni2 high-entropy alloys through engineering phase transformation pathway
Shahryar Mooraj, Xizhen Dong, Shengbiao Zhang, Yanming Zhang, Jie Ren, Shuai Guan, Chenyang Li, Rameshwari Naorem, Nicolas Argibay, Wei Chen, Wentao Yan, Dierk Raabe, Zhongji Sun, Wen Chen, Wen Chen, Wen Chen
Abstract
Abstract The far-from-equilibrium solidification during additive manufacturing often creates large residual stresses that induce solid-state cracking. Here we present a strategy to suppress solid-state cracking in an additively manufactured AlCrFe 2 Ni 2 high-entropy alloy via engineering phase transformation pathway. We investigate the solidification microstructures formed during laser powder-bed fusion and directed energy deposition, encompassing a broad range of cooling rates. At high cooling rates (10 4 −10 6 K/s), we observe a single-phase BCC/B2 microstructure that is susceptible to solid-state cracking. At low cooling rates (10 2 −10 4 K/s), FCC phase precipitates out from the BCC/B2 matrix, resulting in enhanced ductility (~10 %) and resistance to solid-state cracking. Site-specific residual stress/strain analysis reveals that the ductile FCC phase can largely accommodate residual stresses, a feature which helps relieve residual strains within the BCC/B2 phase to prevent cracking. Our work underscores the value of exploiting the toolbox of phase transformation pathway engineering for material design during additive manufacturing.