Effect of the high current pulsed electron beam treatment on the surface microstructure and corrosion resistance of a Mg-4Sm alloy

Surface modifications of a cold rolled 2024 Al alloy by high current pulsed electron beams

“…Thus, the initial lattice parameter of 0.4062 nm decreases to 0.4050 nm,0.4049nm and 0.4053 nm after 6,12and 24 pulses of treatments, respectively. This general trend of the reduction in lattice parameter with the number of pulses is similar to what was reported in previous works on Mg alloys [40,64].…”

“…This can lead to the formation of metastable microstructures such as supersaturated solid solution and nanograins or nanodomains [10,34,38,42,43,46,[65][66][67][68].Meanwhile, the drastic variation of temperature induces dynamic thermal stresses from the surface towards the material core, which leads to plastic deformation and deep hardening at the subsurface [25,30,32,37,42,44,45,62,64,68]. Also, corrosion improvements have often been reported after HCPEB [35,37,40,41,62].…”

“…For example, the cooling rates have been calculated [9,[25][26][27]and investigated experimentally [28] to be of the order of 10 8 -10 9 K/s. Such a drastic temperature variation induces the formation of thermal stresses and shock waves reaching several hundreds of Mpa, which would induce severe surface deformation the materials [29][30][31][32][33].With repeated heating and cooling induced by successive pulsed electron beams irradiation, it has been observed that precipitates are partially or completely dissolved and that chemistry segregations are drastically reduced in the top surface melted layer where supersaturated solid solution can form [34,35].These microstructural changes improve the corrosion resistances of the surface layer which has been established in various alloys such as steels [34][35][36][37], Mg alloys [38][39][40]and Al alloys [41].Besides, due to the effect of dynamic stress fields induced by the drastic thermal processes on the material, plastic deformation occurs at the treated surface and subsurface layers, resulting in surface and subsurface microhardness enhancement [30,37,42].…”

Effect of CeO2 on Corrosion Resistance of High-Current Pulsed Electron Beam Treated Pressureless Sintering Al-20SiC Composites

“…Figure 7b,c, along with the analysis of the corrosion results in Figure 6, show that as the number of pulses increases, the Al matrix composites with the addition of rare-earth elements have a relatively more complete surface with a better protective layer, good micro-structure, and greatly enhanced corrosion resistance compared to those without the addition of rare-earth elements. The improvement in corrosion resistance can be attributed to the following points: after adding rare-earth elements, the micro-structure of the alloy surface improves, the surface is relatively dense and flat, and the corrosive liquid is insulated from the substrate, which is beneficial to reducing pitting corrosion of the alloy surface and improves the passivation performance of the alloy [38]. Rareearth elements not only eliminate micro-cracking but also change the form of corrosion, transforming local corrosion into uniform corrosion and improving corrosion resistance.…”

Improvement of Formability and Corrosion Resistance of Az31 Magnesium Alloy by Pulsed Current-assisted Laser Shock Forming

“…The improvement of the corrosion resistance of magnesium alloys is also a popular research topic. Liu [18] processed magnesium-4Sm alloy using high-current pulsed electron beam, tested the corrosion of the sample through electrochemical test, and found that the corrosion current density decreased, the electrochemical impedance increased, and the corrosion resistance improved. M. Abeens [19] found that the sample grains treated by laser shot peening were re ned, the grain boundary density increased, the crack propagation was delayed, and the corrosion rate was effectively reduced.…”