Treatment of silumin surface by a modulated submillisecond electron beam

Hypereutectic silumin (AlSi20) was exposed to a submillisecond intense electron beam with current modulation on the SOLO plasma-cathode electron source. The beam current was modulated so that the AlSi20 surface was first heated to melting for 200 mu s and then kept at 600 degrees C for 400 and 800 mu s. After such modulated irradiation, the alloy was analyzed to assess its strength, wear resistance, structure, and phase state. The analysis shows that the longer the alloy is kept at 600 degrees C, the higher the alloy microhardness and wear resistance. After modulated irradiation with 600 degrees C kept for 800 mu s, the microhardness of AlSi20 increases 2.2 times, and its wear resistance increases 3.7 times. Within a depth of up to 60 mu m, the surface structure of AlSi20 irradiated in this mode is composed of rapidly solidified cells, and likely, it is this cellular structure which is responsible for the increase in the mechanical and tribological properties of the alloy.