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Structure and Mechanical Properties of Ti<SUB>3</SUB>Al Compact Produced by Hot Pressing of Mechanically Alloyed Powder

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1990

Year

Abstract

The mixture of elemental powder of Ti(70 at%) and Al(30 at%) was offered to a mechanical alloying process. The processed powder was vacuum hot pressed at 1173 K for 3.6 ks under 100 MPa. The compact having relative density of approximately 100% was obtained.The results of X-ray diffraction, TEM observation and energy dispersive X-ray analysis indicated that the compact has an ultra-fine grain (average grain diameter=1.5 μm) structure consisting of Ti3Al intermetallic compound.The compact showed a noticeable high compressive strength (0.2% proof stress=2065 MPa). However, its ductility was rather low (compressive fracture strain was about 5%).During compressive deformation of the compact at 1173 K, a typical dynamic recrystallization which introduce a some extent of grain refinement was observed.Moreover, the compact showed a very large m-value of 0.44 at 1173 K. Then, the compressive deformation of the compact at this temperature was presumably proceeded by superplastic flow which closely related to the dynamic recrystallization behavior.