Microstructure and mechanical behavior of novel high-strength aluminum alloys processed by friction surfacing

this study, the friction surfacing process was investigated to assess its influence on the microstructure evolution and mechanical properties of two novel high-strength aluminum alloys, HighZn + Zr and LowZn + Y, from the feedstock to the deposited and heat-treated states. The results indicate that LowZn + Y exhibited superior deposition performance, achieving higher deposition efficiency and rate while consuming less energy compared to HighZn + Zr. Both alloys experienced significant microstructural refinement during friction surfacing, characterized by fine, equiaxed grains and an inhomogeneous intermetallic particle distribution due to intense shear forces, precipitate dissolution, and dynamic recrystallization. However, subsequent heat treatment led to abnormal grain growth, influenced by the inhomogeneous particle distribution and the extended duration of the thermal exposure. In terms of mechanical properties, both alloys demonstrated increased yield strength, ultimate tensile strength, and maximum elongation in the as-deposited state relative to the feedstock, attributed to grain refinement and improved particle dispersion. After heat treatment, both yield strength and ultimate tensile strength exhibited a slight increase, attributed to the formation of nanometric precipitates. However, maximum elongation decreased as a result of grain coarsening, which promoted plastic strain localization and increased the susceptibility to crack initiation and propagation under mechanical loading.