DEVELOPMENT OF NANOGRAINED. TIAI BY. MECHANICAL ALLOYING

Abstract

Titanium aluminides is a potential candidate for space application. Most of applications are limited due to its poor ductility at room temperature. This report studies the mechanisms of the formation of nano-grained Ti-Al matrix containing titanium (50 at %), aluminum (48 at %) powder with (Ni-P)/graphite—1 at % and 1 at%(Nb,Cr) that was produced through mechanical alloying by using high energy ball milling (HEBM) to produce Ti-Al-(Ni-P)/Gr-(Nb,Cr) intermetallic matrix composite (IMC). Milled graphite (C) was coated with Ni-P by electroless (EL) coating technology. Milling was conducted by using agate balls with parameters of the ball to powder ratio of 5:1, 300 rpm for 250 hours. Phase transformation, surface morphology and elemental composition mapping were characterized using X-ray diffraction, field emission scanning electron microscopy (FESEM) and EDAX analysis and Differential Scanning Calorimetric (DSC) during increasing milling time from 25hrs to250hrs. The results show that formation of nano size particles of TiAl, Ti3A1 phases with increasing milling time.