COMPOSITIONAL RANGE, THERMAL-STABILITY, HARDNESS AND ELECTRICAL-RESISTIVITY OF AMORPHOUS-ALLOYS IN AL-SI (OR GE)-TRANSITION METAL SYSTEMS

An amorphous single phase was formed in wide compositional ranges in rapidly solidified Al-Si-transition metal (M) and Al-Ge-M alloys. The compositional ranges are in the range from 12 to 53 at.% Si or Ge and 8 to 23% M and Al-Si-Co and Al-Ge-Fe alloys have the widest glass-formation ranges. Because the interaction between aluminum and silicon or germanium atoms is thought to be repulsive from the immiscible equilibrium phase diagrams, the glass formation is probably due to an attractive interaction of M-Si (or Ge) and Al-M pairs. Hardness, Hv, and crystallization temperature, Tx, increase with increasing M content and the highest values reach 1120 DPN and 715 K, while the change with silicon or germanium content is smaller for Hv and is hardly seen for Tx. Additionally, the Hv and Tx have maximum values for Al-Si (or Ge)-M (M=Cr, Mn or Fe), decrease with the decrease and increase in the group number of M element and are the lowest for Al-Si (or Ge)-Ni alloys. The compositional dependence is interpreted under the assumption that Tx and Hv of the aluminum-based amorphous alloys are mainly dominated by the attractive interaction of M-(Si or Ge) and Al-M pairs. Room-temperature resistivity, QRT, increases in the range of 220 to 1940 μΩcm with increasing silicon or germanium and M contents.