Effects of melt temperatures on the structure relaxation and compressive plasticity of La62Al14(Cu5/6Ag1/6)14(Ni1/2Co1/2)10 bulk metallic glass

The effects of melt temperatures on the structure relaxation and compressive plasticity of La62Al14(Cu5/6Ag1/6)(14)(Ni1/2Co1/2)(10) bulk metallic glasses (BMGs) were studied by using X-ray diffraction, differential scanning calorimetry, dynamic mechanical analysis and compressive tests. Results indicated that the supercooled region Delta T was enlarged, the thermal stability and glass forming ability were improved, and free volume was enhanced with the increasing melt temperature of the prepared BMGs. Furthermore, compared with other samples, the sample that was subjected to the highest melt temperature showed a pronounced beta-relaxation that was attributable to the large amount of free volume. The fitting of Arrhenius equation revealed that the activation energies of alpha-relaxation (E-alpha) and beta-relaxation (E-beta) decreased with increasing melt temperature, whereas the difference between E-alpha and E-beta increased. Notably, the specific value of the empirical law (E-beta/RTg) decreased with increasing melt temperature, thus indicating that E-beta/RTg may be related to the free volume. Given the pronounced beta-relaxation, BMGs with a higher overheated level exhibited improved compressive plasticity.