Abstract
Thermoelectric power (TEP) measurements for Al-4 wt pct Cu alloy samples in the form of wires 0.5 mm diameter quenched then deformed torsionally to different degrees were carried out after isothermal annealing in the temperature range 383-423 K. Precipitation of excess solute Cu atoms, as traced through TEP measurements, was enhanced by predeformation and attained different stable sizes depending on the annealing temperatures as revealed by the observed final stable TEP values. The energy activating precipitation process was found to be deformation dependent. The time exponent 1.06, as calculated from the volume fraction of Cu atoms precipitated at a certain time to form Guinier-Preston (GP) zones, was found to be independent on predeformation over all the investigated temperature range and consisted with Hams theory for precipitation on dislocations. The results were interpreted on the basis of the dominating diffusion mechanisms and predeformation and the different contributions of the solute atoms when dispersed in the matrix or included in the formed GP zones to the measured TEP. (Author)