The role of microstructure on strength and ductility of hot-extruded mechanically alloyed NiAl

Mechanical alloying followed by hot extrusion has been used to produce very fine-grained NiAl-based alloys containing oxide dispersoids. The dispersoids affect the progress of recrystallization during hot extrusion and contribute to the preservation of the 〈110〉 deformation fiber texture. The 〈110〉 texture enables the activation of 〈110〉 〈100〉 and 110 〈110〉 slip systems. The occurrence of 〈100〉 and 〈110〉 slip dislocations satisfies the von Mises criterion for general plasticity and is postulated to contribute to notable room-temperature compressive ductility of the mechanically alloyed (MA) materials. Another factor likely affecting the compressive ductility is the predominant occurrence of low-angle grain boundaries. The attractive dislocation — dispersoid interactions lead to a ductility trough observed at 800 K in the MA materials. The MA NiAl materials are strong at both ambient and elevated temperatures due to fine grain and the presence of dispersoids and interstitial atoms.