Irradiation-induced atomic migration and its effect on the surface and mechanical properties of laser additive manufactured MWCNTs/Al–Mg–Sc–Zr composites

High radiation environments in space tend to cause complex atomic migration in materials and affect their mechanical properties. In this work, the effect of He ion irradiation on the surface and mechanical properties of Al-Mg-Sc-Zr alloys modified with 0.5 wt.% multi-walled carbon nanotubes (MWCNTs) manufactured by laser powder bed fusion (LPBF) is investigated. The interaction mechanism of He ion irradiation-induced atomic migration in these composites is revealed based on molecular dynamics simulation. The results show that the MWCNT addition tends to effectively adsorb the point defects caused by irradiation, inhibiting the formation of large-size dislocation loops and voids in the matrix. He ion irradiation tends to cause the formation of pits and blisters on the surface of the composites, becoming more pronounced with increasing irradiation dose. As the irradiation dose increases from 0 to 17 dpa, the micro-hardness of the composites increases from 162.9±1.8 HV 0.2 to 166.5±3.2 HV 0.2 and the nano-hardness increases from 1.93±0.03 to 2.08±0.01 GPa, while the elastic modulus slightly decreases from 95.2±1.4 to 90.1±1.2 GPa. This study provides a basis for understanding and developing high-performance (aero)space composites confronted with high irradiation environments.