The thermodynamics of and strengthening due to co-clusters: general theory and application to the case of Al-Cu-Mg alloys
نویسندگان
چکیده
Co-clusters in ternary or higher order metallic alloys are metastable structures involving two or more distinct alloying atoms that retain the structure of the host lattice. A thermodynamic model based on a single interaction energy of dissimilar nearest neighbour interaction energy is presented, and a model for the strengthening due to these co-cluster dimers is derived. The model includes a new treatment of (short-) order strengthening relevant to these co-clusters and further encompasses modulus hardening and chemical hardening. The models are tested against data on a wide range of Al-Cu-Mg alloys treated at temperatures between 20 and 220oC. Both quantitative calorimetry data on the enthalpy change due to co-cluster formation and strengthening due to co-clusters is predicted well. It is shown that in general (short-range) order strengthening will be the main strengthening mechanism.
منابع مشابه
A model for co-clusters and their strengthening in Al–Cu–Mg based alloys: a comparison with experimental data
A model for the thermodynamics of and strengthening due to Cu–Mg co-clusters in Al–Cu– Mg based alloys is analysed and tested. The formulation uses a single interaction enthalpy between dissimilar alloying elements (e.g. Cu and Mg atoms in an Al–Cu–Mg based alloy) combined with the configurational entropy. The metastable solvus in Al–Cu–Mg based alloys is calculated. Recently published small an...
متن کاملA Model for the Thermodynamics of and Strengthening Due to Co‐clusters in Al‐mg‐ Si Based Alloys
An expanded model for the thermodynamics of co-clusters and their strengthening is presented, and the model is applied to predict co-cluster formation and strengthening in AlMg-Si alloys. The models are tested against data on a wide range of Al-Mg-Si alloys aged at room temperature. The strengthening due to co-clusters is predicted well. The formation of the co-clusters is studied in an Al-0.5a...
متن کاملMicrostructure and strength modelling of Al–Cu–Mg alloys during non-isothermal treatments Part 2 – Welds
The present work applies a model for microstructural evolution in the solid state and Al–Cu–Mg alloys and expands it in a computationally efficient way to include solid–liquid reactions in fusion welds. The model is used to predict local strength and hardness of the welds, using a formulation that incorporates hardening due to two types of precipitates, i.e. Cu–Mg co-clusters and the S phase pr...
متن کاملA Model for Precipitation Kinetics and Strengthening in Al-Cu-Mg Alloys
A physically-based numerical model is developed to predict the microstructural evolution and strengthening in Al-Cu-Mg alloys during isothermal treatments. The modelling of the formation kinetics of the precipitates is based on the Kampmann and Wagner model. The strengthening by the shearable Cu:Mg co-clusters is modelled on the basis of modulus strengthening mechanism and the strengthening by ...
متن کاملTHERMAL ANALYSIS AND KINETICS OF THE PRECIPITATION IN WROUGHT Al-Mg, Al-Mg-ScAND Al-Mg-Sc-Me (Me=Zr, Ti) ALLOYS
Precipitation behaviour of wrought Al-6Mg alloys with ternary scandium and quaternary zirconium and titanium has been studied. Hardness measurements and resistivity studies are employed to assess the precipitation behaviour of scandium doped Al-6Mg alloy without or with quaternary additions of zirconium and titanium. Further, the kinetics of precipitations are studied by differential scanning c...
متن کامل