Phase Field Simulation of the Influence of Different Zn Alloying Methods on the Spinodal Decomposition in Mn–Cu–Zn Ternary Damping Alloys

Mn–Cu–Zn alloys, derived from Mn–Cu damping alloys, rely on twinned martensite’s fct structure, formed by fcc lattice distortion in Mn-rich regions. Alloys with intermediate Mn content develop nanoscale Mn-rich areas via aging treatment. To enhance Mn–Cu–Zn alloys, a mathematical model using the Cahn–Hilliard equation was created. It utilized 59Mn41Cu alloy as a base, partially replacing Mn or Cu with 5.5% Zn. Based on the semi-implicit Fourier spectral method, an improved algorithm was developed to extend spectral methods for solving subregion resolution models of the nonlinear Cahn–Hilliard partial differential equations for ternary alloys. This study compares the effects of two different alloying strategies, namely partial substitution of Mn by Zn and partial substitution of Cu by Zn, on the onset of spinodal decomposition during aging of Mn–Cu–Zn ternary alloys. The analysis indicates that the alloying strategy of partial substitution of Mn by Zn favors the progress of spinodal decomposition. This finding provides insights for the design of alloy compositions.