A significant achievement of the PSMGDPP project is the successful design of phase-separated Zr (Y)-Al-Fe MGs by alloying addition with Y, a first in this field. The microstructure of phase-separated nano-amorphous domains has been confirmed by sophisticated experimental characterization techniques including transmission electron microscopy (TEM) and atom probe tomography (APT). The alloys exhibit a typical liquid phase separation-induced two-glassy phase (Zr-rich and Y-rich) structure with droplet-like microstructures (nano-amorphous domains). APT investigations confirm the presence of nanometer-sized Y-enriched clusters in the alloys. Microstructure analysis through TEM and APT revealed that the size of nano-amorphous domains increases with increasing Y addition. A key finding of our investigation is the low Young’s modulus in the range of ~81–91 GPa for these phase-separated MGs, attributed to the presence of mechanically soft, Y-enriched glassy regions. Their modulus is lower than that of Co-Cr-Mo, 316L SS and Ti-6Al-4V commercial implant alloys. The in-situ TEM tensile deformation test shows an improvement in plastic behavior, with the plastic strain nearly doubling, clearly indicating enhanced ductility in the phase-separated MGs. The cytocompatibility evaluation of the MG ribbons shows a higher metabolic activity of HGF cells on the surface of samples. Thus, the two glassy-phase Zr-based MGs exhibit suitable mechanical properties and biocompatibility, making them strong contenders for implant applications. For the fabrication of nano-porous MGs, corrosion results show that adding Y, which promotes phase separation, leads to limited passivation and increased electrochemical reactivity. Notably, the corrosion process is accompanied by a significant increase in surface roughness, as well as the development of porosity.
During the course of our investigation on Ce-Ni-Al (Ga) MGs, a new MG composition, Ce60Ni25Ga15, was observed by complete substitution of Al with Ga. The expansion of the supercooled liquid region provides strong evidence for the better glass-forming ability of the Ce60Ni25Ga15 composition, indicating its potential for enhanced stability and processing characteristics. The Ce-Ni-Al (Ga) MGs do not exhibit phase separation, differing from our earlier work on Ce–Al (Ga) MGs, where phase separation was observed due to changes in the electronic structure of Ce atoms. Deformation in Ce-Ni-Al (Ga) MGs occurs by the evolution of shear bands. The significant improvement in the micro-hardness has been observed by alloying addition with Ga, suggesting an increased resistance to deformation. The magnetic properties of the alloys exhibit paramagnetic characteristics, with magnetization slightly decreasing as Ga content increases. Altogether, this study contributes to the understanding of the microstructural characteristics and the nature of the deformation mechanism in MGs.
