Formation of MgAl2O4 in Al2O3-(Al-4wt.%Mg) composites

✍ Scribed by Ching-Fu Horng; Su-Jien Lin; Kuo-Shung Liu

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 711 KB
• Volume: 150
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(92)90123-i

✦ Synopsis

The Al203 particles are introduced into the AI-4wt.%Mg melt by the "vortex" method. After being cast, AI:Q-(AI-4wt.%Mg) composites are remelted at 700, 750, 800 and 850 °C for different residence times to investigate the formation of MgAI204 (spinel).

The results show that MgAI204 is the unique interface of the A120~-(AI-Mg) composites held at 700-850 °C. Fine MgAl204 crystals grow on the surface of the AI203 particle but, as the holding temperature and the residence time increase, some spinels will form themselves into pyramidal shape. The MgAI204 grows not only at the matrix-particle interface but also on the surface of the composite specimens. The fi)rmation reactions of interracial MgAI204 are as follows:

Mg(l) + 2AI(I) + 202(g)= MgAl204(s) 3Mg(1) + 4A1203(s) = 3MgAI204(s) + 2AI(1) Both of them are equally important.