Effect of Cu addition on the microstructure, thermal physical properties and cyclic ablation of C/C-AlSi composite

Al alloy modified C/C composites are one of the most promising light-weight materials. To understand the influence of alloying, AlSi and AlSiCu melts were pressure infiltrated into porous C/C skeletons respectively and the ablation properties were mainly studied. Results showed that Cu and Al generated Al2Cu in AlSi matrix, and the compression strength of the composite was enhanced while the thermal conductivity and the phase transition temperature decreased. The matrix alloy with Cu softened and melted faster and more during cyclic ablation, which protected the C/C skeleton form thermal stress damage. Thus, the addition of Cu led to a decrease in linear ablation rate. •The micro-scale Al2Cu phases are distributed at the matrix and C-Al interface of C/C-AlSiCu composite.•C/C-AlSiCu has a lower linear ablation rate than C/C-AlSi at the same cyclic ablation environment.•The cyclic ablation behaviors were dominated by the thermal conductivity, specific heat, and phase transition temperature.