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.