Microstructure and mechanical properties of Mg-6Al magnesium alloy with yttrium and neodymium

The effects of rare earth(RE) elements Y and Nd on the microstructure and mechanical properties of Mg-6Al magnesium alloy were investigated.The results show that a proper level of RE elements can obviously ref ine the microstructure of Mg-6Al magnesium alloys,reduce the quantity of β-Mg17Al12 phase and form Al2Y and Al2Nd phases.The combined addition of Y and Nd dramatically enhances the tensile strength of the alloys in the temperature range of 20-175℃.When the content of RE elements is up to 1.8%,the values of tensile strength at room temperature and at 150℃ simultaneously reach their maximum of 253 MPa and 196 MPa,respectively.The main mechanisms of enhancement in the mechanical properties of Mg-6Al alloy with Y and Nd are the grain ref ining strengthening and the dispersion strengthening.

Growth process and corrosion resistance of micro-arc oxidation coating on Mg-Zn-Gd magnesium alloys

A Mg-6Zn-3Gd(mass fraction,%) alloy,noted as ZG63,was coated by different micro-arc oxidation(MAO) processes,and the coating structure and corrosion resistance of the alloy were studied using scanning electron microscopy(SEM),glancing angle X-ray diffractometry(GAXRD) and various electrochemical methods.The micro-arc oxidation process consists of three stages and corresponds with different coating structures.In the initial stage,the coating thickness is linearly increased and is controlled by electrochemical polarization.In the second stage,the coating grows mainly inward and accords with parabolic regularity.In the third stage,the loose coating forms and is controlled by local arc light.The looser coating is mainly composed of MgSiO3 and the compact coating is mainly composed of MgO.From micro-arc oxidation stage to local arc light stage,the corrosion resistance of the coated alloy firstly increases and then decreases.The satisfied corrosion resistance corresponds to the coating time ranging from 6 to10 min.