The influence of rare earth metals on the structure of some rapidly solidified Ge- and Si-based alloys

Ge-rich amorphous alloys containing up to 70 at % Ge were produced by the optimization of the Al, Cr and RE (RE: Rare earth metals) content. Contrary to the Ge-based alloys, no positive influence of RE additions on the glass forming ability (GFA) of the Si-Al-TM and Si-Al alloys (TM: Transition metals) was found. As no split of the first broad peak is seen in the X-ray diffraction patterns taken from the amorphous phase of the Ge-Al-RE alloys, one can suggest that such a feature observed in the Ge-Al-TM and Ge-Al-TM-RE alloys is affected by the presence of 3d TM. Peritectic-type phase transformation, amorphous phase + unknown crystalline phase 1 → unknown crystalline phase 2, was observed in the Ge₆₀Al₂₅La₁₅ alloy and studied. The metastable crystalline phase 2 (Ge₁₂Al₅La₃) was found to have a tetragonal lattice with lattice parameters of a = 0.559 nm and c = 0.528 nm.