Experimental Investigation Of Equilibrium Phase Diagram And Liquidus Surface In The Al-Rich Part Of Al-Cu-Mg-Zn Quaternary System

The purpose of present work is to study the phase equilivria relationship at Al-rich part of Al-Cu-Mg-Zn quaternary system at 400 ℃ isothermal section, the information of liquidus projection and phase transfermation. This work selected the experimental alloys according the calculated phase diagram basing on the A1 data base of Thermo-Cal AB company. Preparing the alloys by a special experimental method which is suitable for activity elements such as Mg and Zn with high volatility and reactivity. The equilibrium and as-cast alloys were measured by combination of experimental methods:optical microscope (OM), X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and differential scanning calorimeter (DSC) et al. The phase equilibria of Al-Cu-Mg-Zn quaternary system at 80 at.% A1 and 400℃ were determined. Beside we deduced the invariant reactions according to the phase transfermation temperature and the solidification information of as-cast alloys.According to present results, the Al2Cu phase contain very small amond solubility of Mg and Zn (<0.5 at.% Mg and about 2 at.% Zn). The Al2CuMg(S) disolve up to 5 at.%Zn。 The study did no observed new quaternary alloys. The boundary compounent Al5Cu6Mg2, MgZn2 (C14) and τ((Al,Cu)49Mg32 and (Al,Zn)49Mg32)) have large third and fourth component solubility. However, the present experimental data could not identified whether these threes phases group with same crystal structure:Al5Cu6Mg2 and Mg2Zn11 (Mg2Zn11), MgZn2 and AlCuMg (Laves C14), (Al,Cu)49Mg32 and (Al,Zn)49Mg32 (τ) are connected to each other in the quarternary system.The imformation of primary phase, liquidus temperature and phase transfermation are summary and present also.