Abstract:Analysis electron microtechnique (AEM) and high resolution electron microtechnique (HREM) studies were conducted on a spray deposition Al-8.5Fe-1.3V-1.7Si(mass fraction, %) alloy to determine the characteristics of the intermetallic phases. The results show that the striking characteristics of the microstructures in as-deposited and as-extruded alloys indicate the presence of a large amounts of homogeneously distributed fine particles and a few coarse particles, while small amount of eutectics consisted of α(Al) and α-AlFeSi are found in local zone in as-deposited alloy. The fine particle is identified to be bcc αAlFeSi phase, and the coarse particles are monoclinic α-A₁₃Fe₄ equilibrium phase, bcc α-AlFeSi phase and newly found hexagonal h-AlFeSi metastable phase. In α-Al₁₃Fe₄, stacking faults on (100) and (001) plane and microtwin on (100) twinning plane are frequently observed. The extra reflection spots in α-AlFeSi reflection pattern can be induced by α-AlFeSi superstructure. The hexagonal metastable phase transforms to bcc phase, and the compositions of two phases are very similar. A close crystallographic orientation relationship between hexagonal and bcc phases are determined, and HREM image shows that the interface between them is coherent.

Key words: Al-Fe-V-Si alloy; spray casting, intermetallic phase, orientation relationship; phase interface