Size-dependent enhancement of plasticity by laser surface melting in Zr55Al10Ni5Cu30 bulk metallic glass

• Laser surface melting has a larger impact on the plasticity of small specimen than that of large one.
• The enhanced plastic strain depends on the volume fraction of influenced zone.
• The enhancement of plasticity was explained by shear–band interactions.

Laser surface melting (LSM) was utilized in Zr55Al10Ni5Cu30 bulk metallic glass (BMG) with different specimen dimensions to explore the influence of the volume fraction of the laser influenced zone on mechanical properties. It was found that the laser treated specimens exhibit significant enhancement in plastic strain as compared to the as-cast ones under compression. This trend is more pronounced in small specimen than in large one. Moreover, the correlation between the enhanced plastic strain and the volume fraction of the influenced zone was revealed. The enhancement firstly rises with the increase in volume fraction, yet keeps an almost constant value. Furthermore, mechanisms of enhanced plasticity were clarified in terms of shear–band interactions which originate from the different compositions and stress states between the influenced zone and the uninfluenced zone. This study is expected to greatly aid in the applications of surface treatments in BMGs.

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