Effect of grain diameter on the tensile characteristics of thermally deformed Ag-4.4 wt% Cu alloy

Tensile characteristics of Ag-4.4 wt% Cu specimens of different grain diameters were investigated at 300, 343, 383, 423 and 463 K. It was found that the strain hardening exponent n, resilience Uy and strain rate ε˙ were increased with increasing grain diameter while a decrease in the yield stress σyσy, fracture stress σfσf and toughness Uf were observed. This was explained in view of the dislocation interaction with the defects and different inclusions in the matrix and the formation of twins. The formation of twins was found accompanied by an abrupt increase in the strain per unit stress (ε/σε/σ) at a critical stress σcσc. The value of σcσc was found to decrease with the increase of grain diameter d. Concentration of the deformation twins was also found to decrease with increasing the grain diameter d. The associated atomic rearrangement during the formation of deformation twins was found thermally activated by activation energy of ∼0.2 eV. The microstructure of Ag-4.4 wt% Cu alloy specimens was performed by optical microscopy.