Steady state creep during transformation in Zn–40 wt% Al and Zn-0.5 wt% Al alloys

Abstract

Apparent steady state creep of Zn–40 wt% Al and Zn–0.5 wt% Al alloys, is studied under different constant stresses ranging from 44.7 to 78.6 MPa near the transformation temperature. The strain rate of the steady state creep is found to be maximum at 523 K for Zn–40 wt% Al alloy at 463 and 533 K for Zn–0.5 wt% Al alloy. The strain rate sensitivity parameter m amounts to 0.5 ± 0.05 at the apparent maximum strain rate peak of Zn–40 wt% Al alloy, and it was equal to 0.3 ± 0.05 and 0.4 ± 0.05, respectively, at the two maxima of strain rate of Zn–0.5 wt% Al alloy. The activation energy of the steady state creep, determined in the vicinity of these peaks amounts to (1.2 ± 0.07) × 10−22 kJ/atom; to (1.3 ± 0.07) × 10−22 kJ/atom and (1.1 ± 0.07) × 10−22 kJ/atom, characterizing dislocation climb along grain boundaries thus causing grain boundary sliding and migration of the dissolved gains into new grains of product phases. Microstructural analysis confirms that the mechanism of grain boundary sliding takes place during apparent steady state transformation creep.

Effect of Structural Transformation on the Mechanical and Electrical Properties of Quenched (Pb - 1.5 wt % Sb) Alloy

“…The first increase until 443 K is attributed to the increase of the dissolution rate of the solute atoms (Sb) in α-phase (Pb-rich phase) by a thermally activated and stress assisted force. The first decrease in their values to minima indicates that the residual internal lattice strain decreased appreciably in the α-phase owing to the relaxation process of the cross-slipping dislocation [21]. These behaviors might be due to the formation of the fine precipitated particles (Sb-rich phase) where they act as scattering centers for the conduction electrons.…”

Effect of Microstructural Variations Developed by heat Treatment On the Mechanical and Electrical Properties of (Pb-1.5 wt % Sb)

“…attributed to the increase of the dissolution rate of the solute atoms (Sb) in αphase (Pb-rich phase) by a thermally activated and stress assisted force. The decreasing in their values to minima indicates that the residual internal lattice strain decreased appreciably in the α -phase owing to the relaxation process of the cross-slipping dislocation [27]. The change in θ 2 ∆ could also be related to the amount of strain in the matrix,which is also affected by the amount of dissolution.…”

Creep and Structure Parameters Near the Transformation Temperature of Sn-1 wt% Pb Alloy

“…where K is a constant and the exponent m is dependent on both the applied stress and the working temperature. The steady state strain rate sensitivity parameter m In order to correlate between transient and steady state creep, the relation [10,11]…”

“…The alloy containing over 90% Sn is known as "pewter". The creep behavior around the transformation temperatures of some important pewters Sn-0.5 and 9 wt.% Zn and Sn-5 wt.% Bi has been investigated [5,6], respectively. The addition of 1 wt.% Pb to 99 wt.% Sn is to reduce progressively the liquidus temperature of the melt [1] to obtain an alloy with melting point (230°C) which has industrial importance.…”