Effect of composing element on microstructure and mechanical properties in Mo-Nb-Hf-Zr-Ti multi-principle component alloys

A series of non-equiatomic Mo-Nb-Hf-Zr-Ti alloys are synthesized to investigate the effects of the concentration variation of each composing elements on the microstructure and mechanical properties. It is found that all studied alloys form single body-centered-cubic (BCC) phase only with the variation of the lattice parameter, which indicates that the concentration variation of each composing elements has no effect on the phase constitutes. All studied alloys exhibit typically dendritic and interdendritic structure while the concentration variation of each composing elements has different effects on the microsegregation. The concentration variation of Zr leads to the most serious microsegregation. Elements with a higher melting point such as Mo and Nb solidify preferentially and thus are enriched in the dendrites. Both the increase and decrease of the concentration of each composing element reduce the hardness and strength of non-equiatomic Mo-Nb-Hf-Zr-Ti alloys compared with the equiatomic MoNbHfZrTi alloy.