Solidification and Liquation Cracking in Welds of High Entropy CoCrFeNiCux Alloys

High entropy CoCrFeNiCux alloys with a Cu molar ratio of x ≈ 0, 0.5, 1, 1.5 and 2 were arc welded. Solidification cracking occurred in the fusion zones of alloys with x ≈ 0.5, 1 and 1.5. Cu-rich material was observed around cracks, increasing in quantity with increasing Cu content. Liquation cracking occurred in the partially melted zone next to the fusion zone, and it propagated into the fusion zone as solidification cracking. A recently proposed index for the susceptibility to solidification cracking was tried, i.e., |dT/d(fS)1/2| near (fS)1/2 = 1, where T is temperature and fS the solid fraction. The index was higher in alloys with x ≈ 0.5, 1.0 and 1.5, consistent with the solidification cracking observed.