A detailed theoretical study was made of the dissolution of precipitates. The kinetic analyses of the atomic mechanisms included the concurrent effects of diffusion, interface reaction, and curvature, and considered the more complex problems of precipitate arrays and nondepleted matrices. The general formalism thus obtained was used to interpret the results of an experimental investigation of the technologically important problem of the dissolution of “reluctantly soluble” carbides in the Fe-C-V system. It was found that vanadium carbide (and iron carbide as well) were quite easily dissolved while complex alloy sulfides, silicates and oxides (possibly associated with the presence of vanadium) persisted, with little if any dissolution. Previous views of the reasons for poor hardenability were reevaluated in light of these results.

Second phase dissolution

For the heat-treatable aluminum alloys containing plate or rod/needle-shaped precipitates, a previous model was modified to present quantitative relationships between the yield strengths of the alloys and the sizes, volume percentages of precipitates, related to aging temperature and aging time as well as alloy compositions, while the strengthening of the precipitates was coupled with the whole evolution process, i.e. nucleation, growth and coarsening, of the precipitates. It was found that the aging yield strengths have been well predicted by the model for a series of aged Al–Cu binary alloys, 6061 alloys and Al–Zn–Mg alloys. It was also experimentally proved that the model was suitable to evaluate the aging strengthening of the precipitates for an Al–Cu–Mg alloy and an Al–Mg–Si alloy. Furthermore, a detailed discussion has been made to the variation of aspect ratio of precipitates, relative to its strengthening response, with aging parameters and alloy compositions.

Modeling the strengthening response to aging process of heat-treatable aluminum alloys containing plate/disc- or rod/needle-shaped precipitates

https://escholarship.org/content/qt7c52q8br/qt7c52q8br.pdf?t=p0hhjg

C.W Haworth

Papers

Dissolution of γ phase in Al-Ag alloys

Dissolution of θ phase in Al-5% Cu