Thermo-mechanical Behavior of HEA Alloys Containing Interdendritic MC Carbides

Casting allows obtaining in situ compositesComposites associating a HEA matrix and refractoryRefractory carbides. The presence of MC carbidesMC carbides allows benefiting simultaneously from the intrinsic good creep resistance of the HEA matrix, and from the delayed {steady state to tertiary} transition of the creep deformation given by the good cohesion between neighbor dendrites. However, the difference in thermal expansion behavior between matrix and carbides may induce curious geometrical behavior of the whole alloy at high temperatureHigh temperature, as earlier found for cobalt-based alloys, for instance. This work aims to investigate the dimensional behaviorDimensional behavior of MC-strengthened HEA alloys at high temperatureHigh temperature during heating and an isothermal stage, in order to observe the consequences of the internal interaction between matrix and carbides, such as visco-plastic deformations. Effectively, in contrast with the carbides-free quinary HEA alloys based on Co, Ni, Fe, Mn and Cr, the alloys with the same compositions as these later ones but containing TaC or HfC carbides behave curiously during heating and during the 1200 °C isothermal stage. Indeed, contraction occurs when arriving to 1200 °C and continues isothermally but slowing down. In parallel, it was also noticed that a decrease in Mn content and an increase in Cr content lowers a little thermal expansion coefficient.