Investigation of in-situ synthesis of NbAl 3/Al 2O 3 nanocomposite by mechanical alloying and its formation mechanism

Abstract

The present study was carried out to synthesize NbAl 3/Al 2O 3 intermetallic matrix nanocomposite by mechanical alloying (MA) using Nb 2O 5 and Al as raw materials. This nanocomposite was produced through a mechanochemical reaction between Nb 2O 5 and Al. The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry and scanning electron microscopy techniques. It was found that the reaction between Al and Nb 2O 5 takes place in an explosive mode after about 450 min of milling time. The milled powder had a microstructure consisting of nanocrystalline NbAl 3 base adjacent to Al 2O 3 particles with a nanoscale grain size. At longer milling times, no changes were observed, except peaks broadening due to the decreasing in crystallite size and increasing in lattice strain. After 15 h of milling time, average crystallite size of NbAl 3 and Al 2O 3 were about 8 and 13 nm, respectively. Heat treatment of powder mixture milled for 15 h showed a good thermal stability for this nanocomposite.