Al–TiO2–Gr powder metallurgy hybrid composites with cold upset forging

Abstract

The cold upsetting studies were carried out for the aluminium metal matrix hybrid composites in the present study. Aluminium metal matrix hybrid composites were synthesised through powder metallurgy route from ball-milled powders to yield the following compositions: Al + 2.5 wt% TiO2 + 2 wt% Gr, Al + 2.5 wt% TiO2 + 4 wt% Gr, Al + 5.0 wt% TiO2 + 2 wt% Gr and Al + 5.0 wt% TiO2 + 4 wt% Gr. The compaction process was carried out using suitable punch and die in 40 kN hydraulic press, and sintering was done in an electric muffle furnace at the temperature of 590 °C for 3 h. The sintered preforms were subjected to incremental compressive loading of 10 kN until the cracks were found at the free surface. The true axial stress, true hoop stress, true hydrostatic stress and true effective stress were calculated for all the preforms, and all these stresses are correlated with the true axial strain. The stress ratio parameters (σ z/σ eff, σ θ/σ eff, σ z/σ m and σ θ/σ m) of the all preforms were correlated with true axial strain. The maximum true axial stress, true hoop stress, true effective stress and hydrostatic static stress are obtained for the composite containing 5 wt% of TiO2 and 4 wt% of graphite and the minimum ones are obtained for composite containing 2.5 wt% of TiO2 and 2 wt% of graphite.