Development And Investigating The Properties In La-Ce-Ni-Cu-Al High-entropy Metallic Glasses

Bulk metallic glasses?BMGs?with a metastable state,and high entropy alloys?HEAs?,which feature high mixing entropy,have attracted considerable research attention owing to their unique mechanical and physical properties.Some alloys have featured characteristics of HEAs and BMGs,and are termed high-entropy BMGs?HE-BMGs?.Rare HE-BMGs were been fabricated in known,and most of them possess high glass transition temperature.Basis of the principle of similitude and Ce-Al-Cu alloy,we designed a new alloy system of La-Ce-Ni-Cu-Al HE-BMGs with very low glass transition temperature?420 K?,wide supercooled liquid region?70 K?and high stability and glass forming ability.We predicting the formation of phases from values of the parameters?and?;our calculations suggested that the HE-BMGs possess a large?value?15%?and a small??0.46?,indicating the formation of intermetallic phases during solidification.The glass formation,mechanical properties,fragility and crystallization kinetics are studied.Compressive testing indicated that the HE-BMGs are ductile on a microscopic scale but brittle on a macroscopic scale,because of the low fragility index m of the HE-BMGs.According to VFT model,the fragility parameter m is the lowest value in known HE-BMGs,which classify our HE-BMGs as strong glasses.We investigated the relationship among glass transition temperature T_g,entropy of mixing S_mix,and fragility parameter m.It can be confirmed that T_g is an important factor relative to the fragility parameter m.The activation energy for glass transition?E_g?is almost proportional to the HE-BMG fracture strength,because a higher E_g is required to dislodge the molecules from the glassy configuration for the HE-BMGs with a high strength.In non-isothermal processes,the Avrami exponents n were⁴?i.e.,>2.5?,indicating that the crystallization process proceeded through high-dimensional nucleation and growth with an increasing nucleation rate.