Effect of Ca and Sr on microstructure and compressive creep property of Mg–4Al–RE alloys

The compressive creep property of Mg–4Al–RE (AE41) alloys is investigated using a homemade compressive creep device. The microstructure of as-cast and post-crept AE41 alloys is observed by scanning electron microscope (SEM), and the precipitation phases in the alloys are analyzed by X-ray diffraction (XRD) and energy dispersive spectrometry (EDS). The results show that the compressive creep rates of AE41 alloys are decreased with increasing duration in the primary creep stage, and the steady state compressive creep rates are decreased with increasing calcium and strontium concentrations. The steady state compressive creep rate of AECJ411202 alloy is 1.36721×10−7 mm/s that is 8.34 times lower than that of AE41 alloy. The poor compressive creep resistance of AE41 alloys is caused by the softening of β-Mg17Al12 phase. The compressive creep resistance of Mg–Al–RE–Ca and Mg–Al–RE–Ca–Sr alloys is improved by the grain refinement, and the granular Al2Nd, bone (Mg, Al)2Ca and fish-bone Al4Sr hindering the dislocation climbing and grain boundary sliding.