Modeling precipitation kinetics in multicomponent alloys during deformation

Abstract

A new mean-field modeling tool is developed to correctly tackle the problem of precipitation during deformation. The model is an extension of a previously developed Langer–Schwartz–Kampmann–Wagner precipitation modeling approach for multicomponent alloys. The latter is now integrated together with Thermo-Calc software and with physically based equations describing the evolution of the dislocation density during hot-working. New equations for the nucleation barrier and the critical size have also been added to correctly simulate the early stages of precipitation. The model is applied to hot compression tests, for which experimental information was available. The model shows the importance of accounting for the overall precipitation kinetics, and not only for constant values of the precipitate volume fraction or size, to investigate the mechanical property evolution. This is due to a complex interplay between the defects and the precipitates’ evolution driven by a competition between thermodynamics and kinetics. Finally, it is highlighted how the strain rate used affects the final microstructure of the material.

DSC Analysis of the Effect of Cold Deformation on the Precipitation Kinetics of a Binary Cu-Sc Alloy

“…This phenomenon was evident due to the evolution of the material properties, namely, the concurrent increase in electrical conductivity and hardness. Furthermore, several previous investigations have shown that a high dislocation density significantly improves the kinetics of precipitation [5,[34][35][36] and recrystallization [33,37,38].…”

“…All plots show straight lines, with high Pearson correlation coefficients of r 2 = 0.991 for the undeformed specimen and r 2 = 0.982 for the cold-rolled specimen. The activation energies were calculated from their slopes, and are listed in dislocation density significantly improves the kinetics of precipitation [5,[34][35][36] and recrystallization [33,37,38].…”

“…There are several hardening mechanisms for copper, which is very soft in its pure state [2], that can bring about the desired properties. One of the most important in this context is precipitation hardening, which allows both, the otherwise conflicting mechanical strength of an alloy and the electrical conductivity to be increased by optimizing the microstructural properties during specific heat treatments [2][3][4][5].…”

DSC Analysis of the Effect of Cold Deformation on the Precipitation Kinetics of a Binary Cu-SC Alloy

“…This can be attributed to the fact that cold rolling introduces various lattice defects such as dislocations and vacancies into the material, which provide additional nucleation sites for precipitation and thus lead to an accelerated reaction. Furthermore, several investigations have shown that a high dislocation density significantly improves the kinetics of precipitation [5,[34][35][36] and recrystallization [33,37,38].…”

“…There are several hardening mechanisms for copper, which is very soft in its pure state [2], to obtain the desired properties. One of the most important hereby is precipitation hardening, which allows both, the otherwise conflicting mechanical strength of an alloy and the electrical conductivity to be increased by optimizing the microstructural properties during specific heat treatments [2][3][4][5].…”