Modification of Structure and Surface Properties of Hypoeutectic Silumin by Intense Pulse Electron Beams

Abstract

MoDification of strUctUre anD sUrface ProPerties of hyPoeUtectic silUMin By intense PUlse electron BeaMs Methods of contemporary physical materials science are applied for the analysis of structural and phase states, tribological and mechanical properties of hypoeutectic silumin treated by electron beams with parameters as follow: energy density-10-35 j/cm 2 , pulse duration-10 µs, number of pulses-3, pulse-repetition frequency-0.3 Hz. The initial structure of silumin comprises grains of aluminiumbased solid solution, eutectic grains, inclusions of silicon and intermetallic compounds with different shapes and sizes. Electron beam treatment (EBT) with energy density of 20-35 j/cm 2 causes melting of the surface layer, dissolution of silicon in clusions and intermetallic compounds. A structure of high-speed cellular crystallization is formed, and submicro-and nanosize particles of the second phase are reprecipitated. An average size of crystallization cells are of 0.3-0.5 µm at the irradiated surface and of 0.4-0.8 µm on the lower edge of the layer with the cellular structure. The graded structure and phase states are analysed at a depth of up to 120 µm. The submicron grains of lamellar eutectic are detected at a depth of 15 µm. The lateral sizes of eutectic lamellae are within the range of 25-50 nm. The study indicates that nanohardness of irradiated silumin changes nonmonotonously and reaches its maximum at a depth of about 30 µm, which is approximately four times higher than hardness in the initial state. Hardness of the layer close to the irradiated surface (that is at a depth of ≈ 5 µm) is higher by a factor of ≈ 1.6 than that of

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

“…Recently, high-current pulsed electron beam technology (HCPEB), a surface modification micro-structure optimization technology, has attracted considerable attention because it is not affected by ion impurities, as ion beam technology is, and it has a much higher energy efficiency than the laser beam [14][15][16]. Ivanov et al used a highcurrent pulsed electron beam to process hypoeutectic Al-Si alloy and found that because of the presence of the submicron Al-based solid solution formed by HCPEB irradiation and nano-scale structure at the grain boundary, the hardness of the surface layer increased by 3.8-4.2 times [17]. During the HCPEB treatment process, the surface can quickly melt and solidify in a short time (the cooling rate is as high as 10 7 -10 9 K/s).…”

Improving the Properties of Laser-Welded Al–Zn–Mg–Cu Alloy Joints by Aging and Double-Sided Ultrasonic Impact Compound Treatment

“…To improve the comprehensive properties of 7075 aluminum alloy joints, post-weld treatment is an ideal and popular method [ 12 , 13 , 14 ]. Many post-weld treatment methods exist for welded joints, such as electron beam treatment [ 15 , 16 ], heat treatment and mechanical treatment. However, welded joints of 7075 aluminum alloy normally undergo post-weld heat and mechanical treatments, of which the heat treatment is usually aging treatment [ 17 , 18 ], and the mechanical treatment usually ultrasonic impact treatment (UIT) [ 19 , 20 ].…”

A New Class of Second-Order Response Surface Designs

“…These sets allow for rates of change and interactions between variables, such as temperature, density, or pressure. This methodology therefore has wide applications such as design optimization in mechanical engineering [1], [2], [3], health engineering [4], materials engineering [5], and applied physics [6], [7]. Box and Behnken in [8] introduced a class of three-level second-order designs (SODs) for fitting second-order response surfaces over a spherical region.…”