| High-current pulsed electron beam (HCPEB), has been applied as a new energy beam with high density in materials research field, Material surface'properties will be enhanced after treated by HCPEB. Nowadays, HCPEB has been drawing an increasing interest to Materials Science investigators. During the process of the incident HCPEB act on the surface of material, a high density of energy flow (108~109 W/cm2) will be deposited just on a very thin layer within a very short time (from few nanoseconds to few microseconds). This energy flow will cause melt, evaporation and fast solidification on materials'surface. Those processes are able enough to cause surface to deform, which will lead to modification of the special effects (enhanced surface hardness, hot corrosion resistance and oxidation resistance).In this article, DD3 nickel-based single crystal super-alloy is studied as the target for treated by HCPEB (with bombardment 1 time; 5 times; 10 times; 20 times). Results of the samples'cross section microhardness testing after treated by HCPEB showed that changes had appeared on the surface and in the cross section. Microhardness was enhanced in several micrometers in near-surface and curves of the microhardness had displayed special distribution: the microhardness of surface was higher than the microhardness of matrix (1 time bombardment exception), minimal value appeared on the cross-section about 50μm from surface, peak value appeared on the cross-section about 100μm from surface, the microhardness of 350μm from surface was about equal to the the microhardness of matrix. Result of corrosion resistance and oxidation resistance experiment showed that corrosion resistance and oxidation resistance had been enhanced apparently with the increase of treatment times. According to the simulation of temperature field in the surface layer of DD3 showed that the starting melted place was 0.4μm below surface, the starting time of melt was 0.2μs and heat affected zone was about 30μm.Transient state of surface, result of treated by HCPEB, is retained well, we can observe many structure defects of different treatment stages by microscopic observation. Changes of microstructure of DD3 after treated by HCPEB were studied by using metallurgical microscope, SEM, TEM, X-ray diffraction instrument, electron back scatter diffraction instrument and positron annihilation instrument in this article. Testing results showed that melting holes of different appearances emerged on the surface, most of the melting holes were crater pattern, ripple fluctuations and droplets were also appeared on the surface. After treated by HCPEB, the surface segregation of the DD3 nickel-based single crystal super-alloy reduced significantly and the surface structure was much more uniform. Surface melt quenched in very fast time for the cooling substrate, non-equilibrium structure (such as microcrystals and nanocrystals) appeared, many vacancies and high density dislocations assembled on the surface of DD3.Changes of microstructure were reasons of enhanced performance. After treated by HCPEB, white layer, structure of texture, sub-boundary and ultra-fine grain emerged on the surface, which increased resistance of corrosion and oxidation. Regularized-γ′phase and a large number of dislocations enhanced microhardness greatly.
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