The Relationship Between Precipitation Phase And Properties In Al-Mg-Si Alloy

Al-Mg-Si (6000series) alloy as a low density, high strength, good toughness system is a hot development and design of new materials in currently. There are many factors affect the mechanical properties of alloy in the future development of new materials,phase space of valence electron structure and interface electronic structure are the basis of many problems.In order to reveal Al-Mg-Si alloy how to strengthen the role of the micro-mechanism more clearly, this paper used the solids and molecules empirical electron theory (EET theory), and TFD academicians method, combined with Becker model to find the relationship between the valence electron structure and interface electronic structure from angle of Al-Mg-Si alloy's micro structure and mechanical properties.The main innovation achievements obtained as follows:1.EET theory and TFD theory are applicatied of Al-Mg-Si alloy in metastable phase pre-β",β",β' of atoms, binding energy and interface electronic structure analysis.The calculation results show that pre-β",β",β' have the strongest covalent bond electron pairs than the Al matrix.The strongest covalent played an important role, that is why strengthening the alloy overall, and melting point, hardness changes also occurred in the corresponding when those phase precipitation.So valence electron structure reveals the role of strengthening and toughening of the alloy.2.Application Becker model to calculate the phase pre-β",β" and the interfacial energy with the Al matrix.For the P'phase,because its substrate is semi-coherent relationship between the grain boundary interface can only be used bighorn algorithm, using the interface is the surface's 1/3 of the relations obtained.According to the above theory is calculated and analysied of the metastable phase pre-β",β",β' precipitation, and the formation of a variety of interface between the matrix alloy combining the stability of precipitation and the precipitation phase order.3.Through the valence electron structure of precipitates and the interfacial electronic structure parameters nA,σN, F,ρ,Δρ,σ,σ' and the interfacial energy y, found in the aging process, when nA is larger, the combination is stronger.We also can using nA/nAα-Al calculated relative precipitation enhancement factor or enhanced effects.When theσN are more, compared with the phase are more stable.WhenΔρless,the average electronic density interface p is bigger,the bonding strength is larger.We can be applied to solid solution strengthening coefficient, coefficient of dispersion strengthening,precipitation enhancement factor to represent the strengthening effect of each phase.By inference, metastable phase pre-β",β" precipitates, and the substrate to form a variety of interface stress between the smaller, more stable interface, make the interface toughness, which is conducive to the strengthening alloy.β', U1and U2 are formed between the matrix and the interface stress is large, is stable under a higher intensity level, have a higher intensity level on the interface strength and toughness, so that the alloy be strengthened.The experimental results reported in the more consistent.Considering all of the precipitated phase alloy, the alloy enhanced the overall variation into account, revealing the alloy microstructure and macroscopic properties of the interface.This paper studies the design of the modified alloy to obtain a high strength and toughness of Al-Mg-Si alloys have important theoretical significance.