The microstructure and mechanical properties of TiAl 3 /Al 2 O 3 in situ composite by combustion process are investigated in details. Pure Al powder and TiO 2 powder were mechanically milled with a molar ratio of 13 : 3 at 300 rpm for 18 ks. This milling powder's green compact coldpressed at 200 MPa for 0.3 ks sintered at 923 to 1173 K for 1.8 ks under Ar atmosphere. The microstructure of the sintered compact was identified by XRD, SEM and TEM/EDS. Mechanical properties were evaluated by Vickers hardness and indentation fracture toughness tests. The compacts at less than 973 K consist of a TiAl 3 phase and remained phases of Al and TiO 2 , while the compact at more than 1023 K consist of TiAl 3 matrix, dispersed Al 2 O 3 particles and some plate like Ti 3 Al phase. The compacts at more than 1023 K have the higher hardness around 800 Hv compared to TiAl 3 single phase compact with 450 Hv. The fracture toughness of TiAl 3 /Al 2 O 3 composite is about two times TiAl 3 single phase compact. This improvement of hardness and toughness is attributed to the effect of the microstructure formation of dispersed Al 2 O 3 particles and Ti 3 Al plate like phase in the TiAl 3 matrix.
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