Morphologies of Microstructure in Mg₉₇Zn₁Y₂ Ribbon upon Ageing at Different Temperatures

Abstract

In order to clarify the morphology of the rapidly-solidified (RS)/melt-spun Mg₉₇Zn₁Y₂ (at%) alloy, which has the secondary phases of long-period stacking (LPS) structure, the ribbon was processed with the thickness of 60 μm and the width of 7 mm, and aged (T5 heat-treated) at different temperatures. The as-spun and aged ribbons were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and laser optical microscopy, and micro-hardness measurement were conducted. It is found that there was a cellular/dendritic transition during melt-spinning process of Mg₉₇Zn₁Y₂ alloy, and a mild age strengthening with the hardness of 113HV/0.05 at 573 K; more importantly, there was a different evolution of morphologies of the matrix and inter-metallic compounds from general secondary phase strengthened alloys when age temperatures up to the 773 K had been introduced to the as-spun alloy.