View the article online for updates and enhancements.
Related contentEffect of strain path change on the texture evolution after cold rolling and recrystallization of Nickel-40 wt. %Cobalt alloy Gyan Shankar and Satyam Suwas -The effect of strain path change on subgrain volume fraction determined from in situ X-ray measurements C Wejdemann, H F Poulsen, U Lienert et al. Abstract. The effect of strain path change on precipitation behaviour of AlCu-Mg-Si alloy was investigated. Two different types of crystallographic textures were produced by changing the strain path during rolling. The deformed samples were subjected to a short recrystallization treatment and ageing to identify the effect of strain path change manifested in terms of crystallographic texture on precipitation behaviour. Preliminary characterization indicates that ageing kinetics as well as precipitate morphology vary depending upon the mode of rolling. The coherency strains associated with a coherent interface is relieved in a unlike manner for differently rolled samples.
IntroductionPrecipitation hardening is produced by solutionizing and quenching an alloy in which the second phase precipitates out upon ageing at intermediate temperature. The requirement of a precipitation-hardening alloy is that the phase diagram should show a solvus viz. solid solubility limit should decrease with decrease in temperature. The driving force behind rejection of excess solutes in the form of the precipitates is supersaturation [1,2]. The sluggish diffusion kinetics at low temperatures ensures that the solute atoms move through only a few tens of interatomic distance [3,4], hence giving rise to precipitation on a very fine scale. The precipitates of the second phase are generally coherent in nature. If the mismatch between the lattice of matrix and precipitate is large, then considerable amount of coherency strain is associated with a coherent interface, giving rise to internal strain hardening. The main contribution to hardening comes from the interaction between the moving dislocations with finely dispersed precipitates [5,6]. The Al 6XXX alloys are precipitation hardenable alloys and precipitation hardening is the key aspect behind high strength to weight ratio of these alloys. The decomposition of supersaturated solid solution occurs is several steps involving transition precipitates before the equilibrium precipitate forms [7,8]. Generally the nucleation barrier for the formation of equilibrium precipitate is too high. The prerequisite of surface energy to create surfaces of critical-sized precipitates dominates over volume Gibbs free energy decrease during the initial stages of precipitation. Usually a sheet of agehardenable material undergoes some sought of thermo-mechanical processing involving deformation at room temperature and ageing at slightly elevated temperature [9,10]. Since the recrystallization temperature is higher than the ageing temperature, the alloy retains the polygonised structure, which has high density of dislocations. Thus, precipitation...