The axial symmetric temperature field model is introduced to describe the evolution of the temperature field during low energy(1～6 J·cm-2)

high current(10～40 kA·cm-2)

short pulse(1～6 μs) electron beam treatment.The simulation indicates that a sublayer about 0.12～0.24 μm in depth and 0～0.13 cm in radial distance in the substrate changes into liquidus state first

and craters are formed due to the liquid volume outbursts similar to the volcano eruption.The final melted layer is about 0.99 μm in depth and 2.01 cm in radial distance.The heating and cooling rates reaching 108～109 K.s-1 should be responsible for the observed grain refinement.