Analyzing the Effects of Milling and Sintering Parameters on Crystalline Phase Evolution and Mechanical Properties of Al86Ni8Y6 and Al86Ni6Y4.5Co2La1.5 Amorphous Ribbons

In the present study, Al86Ni8Y6 and Al86Ni6Y4.5Co2La1.5 bulk amorphous nanocomposites were synthesized by spark plasma sintering of milled melt spun ribbon particles. The as-cast ribbons were of near amorphous nature with minute amount of FCC Al embedded in the amorphous matrix. Milling of the ribbons resulted in partial devitrification due to mechanical crystallization. The milled ribbon particles were sintered in the temperature and pressure range of 300-500 degrees C and 500-700 MPa, respectively. It was observed that nominal amount of amorphous phase was retained at 500 degrees C and 500 MPa. With increase in sintering pressure and decrease in sintering temperature, the amount of crystalline phase evolution decreased, and maximum amount of amorphous phase was retained at 300 degrees C and 700 MPa. The microstructure consisting of amorphous phase embedded with hard intermetallic phases led to increase in the nanohardness of Al86Ni8Y6 and Al86Ni6Y4.5Co2La1.5 as-cast ribbons from 3.26 +/- 0.59 GPa and 3.81 +/- 0.58 GPa to 6.06 +/- 0.70 GPa and 6.14 +/- 0.82 GPa, respectively, for the corresponding consolidated amorphous nanocomposite. Microhardness of the three and five component system bulk samples was 4.19 +/- 0.13 GPa and 3.6 +/- 0.13 GPa, respectively.