The microstructure and thermo-physical properties of Mg-15Ca-15Zn-6Cu phase change heat storage alloy were investigated by optical microscope（OM）

X-ray diffraction（XRD）and differential thermal scanner（DSC）.By the experiment of melting/freezing thermal cycle

thermal cycling stability of the alloy was analyzed.The results show that

after 1 000 thermal cycles

the phase change temperature and phase change latent heat reach 510.2 ℃ and 198.7J/g

respectivly.Compared with the primary alloy

the phase transition temperature is increased by 5.5%

and phase change latent heat is decreased by5.56%

so the Mg-15Ca-15Zn-6Cu alloy exhibits satisfied thermal cycling stability.