Thermal stability and mechanical properties of Al-based amorphous alloys

Thermal stability and mechanical properties of Al85Y10Ni5, Al85Y5Ni10 and Al85Y5Ni9Si1 amorphous ribbons have been examined. During continuous heating, three exothermic crystallization peaks were observed for all alloys. Crystallization onset temperature (Tx) increased from 450 K for Al85Y5Ni9Si1 to 517 K for Al85Y10Ni5. This indicates that the thermal stability of the amorphous phase increased with increasing Y content from 5 to 10 at.%, whereas the substitution of Si for Ni decreased the stability of the amorphous phase. Activation energies for the first crystallization peaks determined by Kissinger and Ozawa methods give good agreement. Tensile strength (σf) and Vickers hardness (Hv) for these Al-based amorphous alloys are about ∼1000 MPa and ∼380 DPN respectively, which is twice as large as conventional Al-based crystalline alloys, while Young’s modulus (E) is higher or comparable to that of pure Al.