Quantitative microstructure study of melt-spun Mg65Cu25Y10

Abstract

Mg 65 Cu 25 Y 10 ribbons were produced by melt spinning. XRD, DSC, HRSEM and HRTEM were used to investigate their microstructure in its as-cast condition as well as after 3-and 6-minute exposures to 100 °C, 120 °C, 150 °C, 200 °C and 300 °C. XRD and DSC studies showed that the as-cast material had an amorphous character; the HRTEM investigation revealed that although the as-cast Mg 65 Cu 25 Y 10 is known to be one of the best glass formers, it is nano-crystalline rather than amorphous. The fraction of the crystalline phase after each treatment was calculated by means of quantitative analysis that took into account the degree of crystallinity of the as-cast material as revealed by HRTEM. The current study showed that quantitative analysis may lead to serious errors when relying on the absence of crystalline peaks in the XRD spectrum as if the material is completely amorphous. Moreover, it seems that HRTEM examination is essential for carrying out quantitative XRD and DSC analyses.