Papers by Keyword: High Current Pulsed Electron Beam (HCPEB)

Abstract: The surface of 3Cr13 martensitic stainless steel was irradiated by high current pulsed electron beam (HCPEB). The microstructures of the irradiation surface were characterized by X-ray diffraction and electron microscopy. After HCPEB irradiation, formation of a melting layer with depth of about 4 μm on the irradiated surface was determined. Further microstructural investigations indicate that the surface melted layer consists of nanoaustenite and ultrafine carbide particles, which primarily appear at grain boundary triple junction. Additionally, the microhardness and corrosion resistance of the irradiated surfaces was improved significantly. The formation of the nanoaustenite layer induced by HCPEB irradiation was believed to be the dominating reasons for the improvement of comprehensive performance of the material surface.

Abstract: AISI 304L austenite stainless steel was irradiated by a high-current pulsed electron beam (HCPEB) source in different process. The microstructures were investigated in detail by electron microscopy. The changes of hardness and corrosion resistance induced by irradiation were also tested. The relationship between corrosion resistance and the microstructures has been explored. The experimental results demonstrate the potential of proper HCPEB processing for improving the hardness and corrosion resistance of metallic materials.

Abstract: Polycrystalline pure titanium was irradiated by high-current pulsed electron beam (HCPEB). The microstructure changes and material strength were investigated by using microhardness tester, optical microscope, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) technique. The experimental results indicate that many craters are inevitably formed on the irradiated surface. The eruption of the craters makes the material surface cleaned, which can improve the corrosion resistance of materials. Furthermore, martensitic structure, ultra-fine grains and high-density dislocations are formed on the irradiated surface, which increase the hardness of the treated samples. The microhardness of 20-pulsed sample reaches 286Hv, which is 71% higher than the initial sample. Martensitic transformation, grain refinement and dislocation strengthening induced by HCPEB treatment are the dominating mechanism for the improvements of material strength. It is suggested that HCPEB technique is becoming an effective approach to surface modification for pure titanium and titanium alloy.

Abstract: The nanocrystalline surface was obtained on bulk pure nickel by using high-current pulsed electron beam (HCPEB) technique. The temperature field induced by HCPEB was numerically simulated. The structures of the nanocrystallized surface were characterized by scanning electron beam (SEM), which showed that after HCPEB irradiation, the initial coarse-grained structure on the surface was refined into fine grains with sizes of about 70nm. It was revealed that melting surface caused by HCPEB irradiation and subsequently rapid cooling was the dominant mechanism of the surface nanocrystallization of bulk nickel. The HCPEB technique provides a new method for rapid fabricating surface-nanocrystallized materials.

Abstract: The Mechanism of Micropores Formed on the Surface of Polycrystalline Pure Nickel under High-current Pulsed Electron Beam (HCPEB) Irradiation Is Explained. it Is Discovered that Dispersed Micropores with Sizes of 0.1-2.0 µm on the Irradiated Surface of Pure Nickel Can Be Successfully Fabricated after HCPEB Irradiation. the Dominant Formation Mechanism of the Surface Micropores Should Be Attributed to the Formation of Supersaturation Vacancies within the near Surface during the HCPEB Irradiation and the Migration of Vacancies along Grain Boundaries and/or Dislocations towards the Irradiated Surface. it Is Expected that the HCPEB Technique Will Become a New Method for the Rapid Synthesis of Surface Porous Materials.

Abstract: The influence of Nd on structure and properties of hypereutectic Al-Si alloys (Al-17.5%Si, Al-25%Si) was investigated in this paper. For Al-17.5%Si alloy, there is no obvious variation in morphology of primary Si before and after Nd modification, but the average size of primary Si is decreased from 34.73µm to 23.39µm after 0.3%Nd modification. Compared with initial sample, the tensile strength and yield strength of 0.3%Nd-modified sample are increased by 11.6% and 1.5%, and wear resistance of Al-17.5%Si alloy is enhanced to a factor of 2.1 after 0.3%Nd modification. However, for Al-25%Si alloy, the tensile strength and yield strength of 0.3%Nd-modified sample are respectively improved by 22.1% and 9.5% as compared to initial sample. Meanwhile, wear resistance of modified sample is improved to a factor of 3 relative to initial sample. The property improvement of two alloys can be attributed to the change in morphology and size of primary Si after Nd modification.

Abstract: The surface irradiation of 6063 aluminum alloy by high current pulsed electron was conducted with the aim of replacing the complicated pre-treatment in the processes of electroless plating. To explore the microstructure changes, optical metallography, SEM (scanning electron microscope), XRD (X-ray diffraction) analyses were carried out, and the sliding tests were used for the detection of wear resistance. It was concluded that the HCPEB irradiation could replace the pre-treatment of aluminum substrate as required in conventional electroless plating with a decreased surface roughness of Ni-P alloy plating layer. The plates exhibited an amorphous microstructure as demonstrated by XRD analysis. The plates, produced with the routine of HCPEB irradiation, activation and electroless plating possess, also exhibited good quality, even better than that of conventional electroless plating technique.

Abstract: High current pulsed electron beam (HCPEB) has been developed as a useful tool for surface treatment of materials. In the present work, the fundamental principle of HCPEB source was described along with the device configuration and working parameters. Through the different kinds of HCPEB surface treatment experiments conducted, the enhanced surface properties induced by HPCEB treatment were illustrated and explained with their microstructure characterization results.

Abstract: The paper reports an analysis of the effect of high current pulsed electron beam(HCPEB) on microstructure transformations and wear resistance of hypereutectic Al-Si alloys. HCPEB treatment with 2.5 J /cm2 energy density leads to the formation of “halo” centered on primary Si, composition homogeneity, the formation of supersaturated solid solution of Al and grain refinement of top melted surface layer. The wear resistance of 15 pulse-treated Al-17.5Si and Al-20Si alloys is drastically improved by a factor of 6.5 and 2, respectively. The increase of hardness in modified surface layer has a positive effect on wear of hypereutectic Al-Si alloys.

Abstract: High current pulsed electron beam (HCPEB), a novel high-power energetic beam technology, has been developed as a useful tool for surface modification of materials. In the present work, the effect of HCPEB treatment on microstructure and wear resistance of Al-15Si and ZK60-1Y Mg alloys was investigated. The results show that a supersaturated solid solution of (Al) and (Mg) is formed on top surface of melted layer induced by rapid heating and cooling during HCPEB process. In addition, the melted layer of approximately 5~11μm thickness is obtained on the ZK60-1Y Mg alloy surface. Wear resistance of Al-15Si and ZK60-1Y Mg alloys are significantly improved after HCPEB treatment. It is demonstrated that HCPEB technology has a good application future in enhancing surface properties of Al-Si and Mg alloys.