Modelling of non-isothermal transformations in alloys containing a particle distribution

An Extended Age-Hardening Model for Al-Mg-Si Alloys Incorporating the Room-Temperature Storage and Cold Deformation Process Stages

“…Hence, the natural aging and artificial aging models contain separate nucleation and rate laws and input data but are linked together via the continuity equation which keeps a record of the amount of solute being tied-up as precipitates. [20,44,45] This allows the mean solute concentration in the aluminum matrix C to be computed and shared among the two populations of precipitates. The equilibrium magnesium concentration at the particle/matrix interface C e Mg is, in turn, calculated via the extended thermodynamic model, which is based on a simplified quasi-binary description of the phase relations.…”

“…Also in the extended artificial aging model, the rate controlling step is assumed to be diffusion of magnesium to the particle/matrix interface, analogous to that done in NaMo-Version 1. [20][21][22]28,29] The way the different models in NaMo-Version 2 are structured and coupled is further illustrated and elaborated below.…”

“…[20,29] The only difference is the expression for the magnesium diffusion coefficient, which in NaMo-Version 2 is modified in order to allow for pipe diffusion through the dislocation core following cold deformation. In this case, the relationship between the effective diffusion coefficient D eff Mg , the bulk diffusion coefficient D Mg , the core diffusion coefficient D c…”

“…[11][12][13][14][15][16][17][18][19] In the past, the relevant structure-property relationships have been captured mathematically in the combined precipitation, yield strength (YS), and work-hardening (WH) model being developed by two of the authors. [20][21][22] Later, it has been renamed the nanostructure model (NaMo) in order to reach out to a wider audience and make the work accessible to people with a background in finite element simulations and advanced structural analyses as well. [23][24][25][26][27] Referring to Figure 1, NaMo-Version 1 divides the age-hardening process into two main stages, i.e., the solution heat treatment (SHT) stage and the artificial aging (AA) stage, based on a simplified description of the artificial aging reaction sequence.…”

“…[23][24][25][26][27] Referring to Figure 1, NaMo-Version 1 divides the age-hardening process into two main stages, i.e., the solution heat treatment (SHT) stage and the artificial aging (AA) stage, based on a simplified description of the artificial aging reaction sequence. [20][21][22] At the same time, the important alloy composition dependence of the artificial aging reactions is accounted for through the use of a separate thermodynamic (TD) model, which provides quantitative information about the thermal stability of the different stable and metastable precipitates involved. Furthermore, if NaMo is used in combination with a numerical thermal (TH) model like, for example, WeldSim, the subsequent response of the alloys to welding (W) and post-weld heat treatment (PWHT) can be simulated.…”