Influence of diffusivity, elastic modulus, and stacking fault energy on the high temperature creep behavior of alpha brasses

Abstract

The steady state creep behavior of three compositions of alpha-brass (90, 80, and 70 at.% Cu) was investigated in the temperature range 550–700°C. Compressional creep testing was performed in dry, deoxidized hydrogen at stresses of 2800, 3400 and 4000 psi. Activation energies for creep were observed to be 38,600, 38,000 and 31,000 cal/mole for alloys containing 90, 80 and 70 at. % Cu, respectively. As these values closely approximate chemical diffusion activation energies, it is thought that the rate controlling mechanism in creep of alpha-brass in the stress and temperature range studied is diffusion dependent. The steady state creep rates ϵ ̇ 3 , satisfied the relationship, ϵ ̇ 3 = Bγ 3.5(σlE) 5D , where B is a constant about equal to 4.4 × 10 17 cm 5 ergs −3.5, γ is the stacking fault energy, σ is the applied creep stress, E is the isotropic, polycrystalline, unrelaxed elastic modulus, and D is the chemical diffusion coefficient.