Distinctive Slow β Relaxation and Its Impact on Mechanical Property of LaCe Based Bulk Metallic Glasses

The slow beta relaxation which occurring at temperatures far below glass transition temperature, typically playing important roles in the plastic deformation behavior of metallic glasses. Compared with polymer glasses, most of the metallic glasses do not exhibit obvious beta relaxation based on dynamic mechanical analysis. In the current work, prominent beta relaxation behaviors of a series (LaxCe100-x) Al10Co25(x = 50, 60, 70, 80) bulk metallic glasses (BMGs) at low temperature are observed using dynamic mechanical analysis. Compared with other BMGs, the LaCe based BMGs show a pronounced beta relaxation peak and relative low peak temperature, the activation energy of the beta relaxation based on Arrhenius equation are calculated around 79.3 kJ/mol to 86.4 kJ/mol, which obey an empirical rule thatE(beta) approximate to (26 +/- 4) RTg, with the coefficient of 23. Experimental results from room temperature compression tests for the LaCe based BMGs indicate that low temperature activated beta relaxation behaviors facilitate the good plasticity of the LaCe based BMGs.