Microstructure and mechanical properties of Al-Si-X alloys fabricated by gas atomization and extrusion process

In order to develop good wear resistant and high-strength alloys, Al81Si19 alloy was reinforced with transition elements such as Ni and Ce. The solubility of Si in aluminum was amplified, with increasing the Ni and Ce content in the rapidly solidified powders. The extruded bars consist of homogeneously dispersed fine Si particles along with Al3Ni and Al3Ce compounds (30-120 nm) in aluminum matrix (grain size below 500 nm). The tensile strength at room temperature for Al81Si19, Al78Si19Ni2Ce0.5 and Al76Si19Ni4Ce1 bars extruded at 400 °C was estimated as 281, 521, and 668 MPa, respectively. In addition, the maximum tensile strength of 730 MPa was attained in Al73Si19Ni7Ce1 bulk alloy. The uniform dispersion of precipitates (Si, Al3Ni and Al3Ce particles) from the supersaturated Al matrix of ternary and quaternary alloys after extrusion was effective for enhanced mechanical properties.