镁合金压铸件化成后表面白斑形成机理 The Forming Mechanism of the White Spot on the Chemical Conversion Coating of the Die-Casting Magnesium Alloy

本文研究了镁合金压铸件化成处理后表面白斑形成机理，对其形态和组织进行了SEM及金相显微观察，并对其表面进行了粗糙度分析试验。结果表明：异型大块α相是白斑形成的主要原因，而白斑出现的本质是在压铸过程中，由于模具表面温度不一致，使得铸件表面形成粗大的先析α相，改变喷涂离型剂方法可消除此种不良现象。 The forming mechanism of the white spot of the die-casting magnesium was investigated by means of SEM andOM.The roughness of the white spot was also tested. It indicated that the larger α phase caused by the uneven temperature distribution of the die result in the formation of the white spot. It can be improved by changing the agent spaying parameter.