Fabrication and Microstructure of Layers Containing Intermetallic Phases on Magnesium

Abstract

Al- and Al/Zn-enriched layers containing intermetallic phases were deposited on the Mg substrate by heating the Mg specimens in contact with the powdered materials in a vacuum furnace. The Al-enriched surface layers were produced using Al powder, whereas the Al/Znenriched layers were obtained from an 80 wt.% Al + 20 wt.% Zn powder mixture. The microstructure and composition of the layers were analyzed by optical microscopy, scanning electron microscopy and X-ray diffraction. The results showed that the Al-enriched layer comprised an Mg17Al12 intermetallic phase and a solid solution of Al in Mg. The layer obtained from the Al+Zn powder mixture was composed of Mg-Al-Zn intermetalic phases and a solid solution of Al and Zn in Mg. Adding 20% of Zn into the Al powder resulted in the formation of a considerably thicker layer. Moreover, the hardness of the surface layers was much higher than that of the Mg substrate.

Archives of Foundry Engineering

“…Even though detailed casting features of conventional particle reinforced Al matrix composites have been examined for many years [9][10][11], efforts on AMSFs have performed usually on their mechanical properties. AMSFs are typically manufactured by infiltration casting or stirring technique.…”

Mould Components Impact on Structure and Quality of Elektron 21 Alloy

“…What is more, magnesium alloys exhibit good technological properties, such as castability, weldability and machinabilty [2,3]. Their main disadvantages are weak corrosion resistance and low maximum working temperatures [4]. Recently, the most widely used magnesium alloys are these with aluminium, zinc and manganese additions [5].…”

“…Addition of rare earth elements reduces alloy susceptibility to shrinkage porosity formation and castings hot cracking [5]. Despite good casting properties -good dimension accuracy and and small solidification shrinkage, magnesium is extremely difficult to cast because of dramatic oxygenation in liquid state [4,6,8,13]. It leads to formation of non-metallic inclusion present in the structure of the castings.…”

Formation of Al-alloyed Layer on Magnesium with Use of Casting Techniques

“…Al-enriched layers can be produced using various methods, e.g. laser surface alloying/cladding [3][4][5], diffusion treatment in molten salts [6,7], diffusion aluminizing treatment [8][9][10][11][12][13][14][15], PVD combined with annealing [16][17], cold spray with subsequent heat treatment [18,19], welding [20], and electrodeposition [21]. The findings reported in the above works suggest that it is the Mg-Al intermetallic phases forming in the microstructure of Al-enriched layers that are responsible for an increase in the hardness as well as corrosion and wear resistance of magnesium and magnesium alloy products.…”