Formation of Intermetallic Nanostructures in Lightweight Ti-Mg-Si Alloys by Mechanical Alloying and Subsequent Consolidation

摘要

Mechanical alloying and Hot Isostatic Pressing were used as processing techniques for the synthesis of Ti-Mg-Si (Ti-rich) lightweight alloys. The samples were analysed by means of electron probe microanalysis, X-ray diffraction, scanning electron microscopy and thermal analysis. The results show that a supersaturated amorphous structure was produced during milling of the Ti{sub}75Mg{sub}13Si{sub}12 mixture, which crystallizes at about 550°C, giving rise to a dispersion of Ti{sub}5Si{sub}3 in a α-Ti matrix. A metastable (Ti,Mg){sub}5Si{sub}3 intermetallic was observed to form during milling of the Ti{sub}60Mg{sub}10Si{sub}30 sample obtained by two different milling processing routes: (i) from elemental powders and (ii) from titanium hydride instead of titanium. The (Ti,Mg){sub}5Si{sub}3 intermetallic decomposes into Ti{sub}5Si{sub}3 and Mg{sub}2Si in the temperature range of 600-700°C. Based on these results, the samples were HIP'ed at 800°C.