Effect of semi-solid reciprocating extrusion on microstructure and properties of Al2O3p/7055 composites

Abstract

Semi-solid reciprocating extrusion technique has been proposed to successfully prepare in-situ nano-Al2O3 particle reinforced 7055 aluminum matrix composites from Al–ZnO reaction system. It is demonstrated that the distribution of Al2O3 particles in the matrix is improved and the matrix grains are refined significantly via semi-solid reciprocating extrusion. After 2 extrusion passes, the average grain size of the matrix was reduced to 17.34 μm, the density of the composite increased to 98.9 %, and the Al2O3 particles in the matrix exhibited the most uniform distribution. After forging and heat treatment, the density of Al2O3p/7055 composite with 2 passes of semi-solid reciprocating extrusion increased to 99.2 %. The composite achieved a tensile strength of 631.2 MPa and a Vickers hardness of 201.5 HV, which are 10.3 % and 17.9 % higher than those of 7055 aluminum alloys, while also 13.8 % and 67.5 % higher than those of composites without semi-solid reciprocating extrusion.

Keywords

• Semi-solid reciprocating extrusion
• Aluminum matrix composites
• In-situ nano-Al2O3 particles
• Density
• Microstructure
• Mechanical properties