Effect of Adding Cobalt on the Mechanical and Structural Properties of Cu-2wt% Be Alloy

Abstract

The aim of the present work is to establish a conelation between the changes in mechanical properties represented by the proof stress <J0.2 , fracture stress <Jr and fracture strain percent Er%, as deduced from the stress-strain curve, calculated fracture surface energy Yr and coefficient of work-hardening Xp with the associated variations in lattice structure by studying the ageing characteristics of Cu-2wt% Be alloy through optical and electron microscope investigations. The work-hardening mechanisms involved during deformation under different testing conditions were elucidated. The effect of adding 0.3wt% cobalt to Cu-2wt%Be alloy was also traced.

The alloys used in the present study were prepared by melting the appropriate amounts of constituents and then homogenized at I 073 K for 2 hours, and swagged by cold drawing to wires of 0.35 mm in diameter or rolled into sheets of 0.2 nun in thickness for metallurgical investigations. The tested specimens were heated above the solvus and then quenched rapidly in water at 273 K to maintain the material in a state of a super-saturated solid solution. This treatment brought the specimens always to an indentical initial state. :