Microstructure and mechanical properties of an in-situ TiB2/Al-Zn-Mg-Cu-Zr composite fabricated by Melt-SHS process

A 10 vol% TiB2/Al-Zn-Mg-Cu-Zr composite was prepared by Melt-SHS techniques. The microstructures and mechanical properties of the composite were analyzed in this work. The results show that TiB2 particles with an average particle size of 0.67 µm are dispersed in the composite uniformly well combined with the matrix alloy after hot extrusion and T6 treatment. The addition of TiB2 particles resulted in a grain size reduction by 64.4%. The hardness, UTS, TYS and elastic modulus of the composite are increased by 9%, 20.2%, 22.3% and 24.6%, respectively. However, the elongation is reduced with the addition of TiB2 particles. The improvement of yield strength is attributed to the uniform dispersion of the fine TiB2 particles in the alloy matrix and the major contribution is from the dislocation strengthening mechanism, which has an additional contribution of 13.8%. In addition, the Orowan strengthening mechanism, grain refinement and load bearing strengthening mechanism have also contributed.