The Paton Welding Journal, 2017, №02



2017 №02 (05)

DOI of Article 10.15407/tpwj2017.02.06

2017 №02 (07)

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The Paton Welding Journal, 2017, #2, 28-32 pages
 

Formation of diffusion zone in welded joints of porous aluminium alloy with monolithic magnesium alloy at chemical activation by gallium

Yu.V. Falchenko, M.A. Khokhlov, Yu.A. Khokhlova And V.S. Sinyuk

E.O. Paton Electric Welding Institute, NASU 11 Kazimir Malevich Str., 03680, Kiev, Ukraine. E-mail: office@paton.kiev.ua
 
Abstract
Comprehensive investigation of mechanical and physical properties of diffusion zone of the produced joints was performed as part of fulfillment of the technological task, namely producing superlight welded structures from porous aluminium alloys of Al–Mg–Zn system and monolithic magnesium alloys (ML4 standard alloy of Mg–Al–Zn system and experimental alloys of Mg–Ga system). The objective of the study was evaluation of the influence of heating cycle, characteristic for different welding processes, on the joints. Welding was performed by two methods with maximum heating temperature up to 300 °C: diffusion welding with long-term cycle of heating in vacuum, and welding with heating by passing current in air, which is characterized by short heating cycle. Gallium was used for forming a monolithic joint and diffusion activation. It is found that a diffusion zone about 10 mm wide forms on porous aluminium side, with slight lowering of micromechanical properties in pore walls, that is typical for aluminium alloys at contact with gallium. In magnesium alloys, an extended (60–100 mm) wavy intermetallic-strengthened diffusion zone forms along the joint line in both the welding processes, mostly of Mg₅Ga₂ composition with melting temperature of 456 °C that is higher than the welding temperature. Thus, the possibility of joining porous alloys to monolithic ones is shown at their slight heating and chemical activation of the joint zone by gallium. 11 Ref., 1 Table, 8 Figures.
 
Keywords: magnesium, porous aluminium, gallium, diffusion welding, welding with heating by passing current
 
 
Received: 21.12.16
Published: 16.03.17
 
 
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