Mechanical behavior and microstructure of Al-10wt. % Nb alloy fabricated by mechanical alloying

Al-10%Nb alloy powders were fabricated by mechanical alloying and their mechanical behavior and microstructure were investigated by means of tensile testing, differential scanning calorimetry, X-ray diffraction and electron microscopy. An intermetallic compound of Al3Nb was partially formed in the mechanically alloyed powders. The grain size was 50 nm after mechanical alloying for 20 hours, and increased to 500 nm after hot extrusion at 400 degrees C. However the 20 size of the intermetallic compounds of precipitated Al3Nb in an Al matrix, did not vary with hot extrusion. The density of the consolidated Al-Nb alloy was over 97% relatively with hot extrusion. Both the tensile strength and elongation decreased at the elevated temperature. As the temperature increased, the dimples in the fracture surface were large and of coalescent shape, and the fracture was caused by the precipitated phases of Al3Nb.