Ca 첨가한 AZ91 마그네슘 합금 용탕의 산화거동

The effects of Ca addition on the liquid oxidation behaviors of AZ91 alloys have been investigated. The oxide layers formed on the molten Ca-containing AZ91 alloys were investigated by using scanning electron microscope and Auger electron spectroscopy in order to elucidate the effect of Ca additions on the ignition and burning of the molten alloys. The thermogravimetric measurements indicated that Ca-containing AZ91 alloys have good oxidation resistance. AES depth analysis revealed that the oxide layers on the molten Ca-containing AZ91 alloys consisted of several layers; the outer layer mainly consisted of CaO and the inner layer was mainly a mixture of CaO-MgO and Al₂O₃. The formation of protective CaO in the oxide layer was directly responsible for improved oxidation resistance of the Ca-containing AZ91 alloys.