Influence of heat treatments on incipient melting structures of DD5 nickel-based single crystal superalloy

The evolution of microstructure and formation mechanism incipient melting DD5 single crystal superalloy during solution heat treatment were studied by scanning electron microscopy (SEM), probe microanalysis (EPMA), energy dispersive spectroscopy (EDS). solidus liquidus alloy obtained differential calorimetry (DSC). Results show that the mosaic-like eutectic fan-like are dissolved at first, coarse γ′ phase is later 1,390 °C/2 h+1,310 °C/4 h+1,320 °C/10 h + air cooling (AC). composition segregations Al, Ta, W Re 0.99, 0.96, 1.04 1.16, respectively, which close to 1. caused low local temperature alloy, micropore region with a lower point preferred position for melting.