Formation of intermetallic compound coating on magnesium AZ91 cast alloy

• Published in: IOP conference series. Materials Science and Engineering 2009-08, Vol.4 (1), p.012024-6
• Main Authors: Zhu, Tianping, Gao, Wei
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum; Casting alloys; Corrosion resistance; Diffusion coatings; Heat treatment; Immersion tests (corrosion); Intermetallic compounds; Magnesium base alloys; Mechanical properties; Saline water; Substrates; Water immersion
• ISSN: 1757-899X; 1757-8981; 1757-899X
• DOI: 10.1088/1757-899X/4/1/012024

This study describes an intermetallic compound coating formed on AZ91 Mg cast alloy. The Al sputtered on AZ91 cast alloy reacted with substrate during a short period of heat treatment at 435°C, resulting in the formation of a continuous intermetallic compound layer. The short period treatment has the advantage of minimizing the negative effect on the microstructure of substrate and the mechanical properties, comparing with the reported diffusion coatings. DSC measurement and examination on the cross-section of Al sputtered samples show that local melting occurred along the Al/substrate interface at the temperature range between 430∼435°C. The formation mechanism of intermetallic compound coating is proposed in terms of the local melting at Al/substrate interface. The salt water immersion test showed significant improvement in corrosion resistance of the intermetallic compound coated AZ91 cast alloy compared with the as-cast alloys.