On the peritectic dissolution of tungsten in liquid Al

DOI: 10.62564/M4-TS1423

Vladyslav Mazur, Tetiana Soloviova

National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute»


When manufacturing heat-resistant metal alloys based on the Ti-Al-W system, technological difficulties arise, which are due to the large difference in the physical properties of the alloy components. The difference in melting temperature causes intense evaporation of the low-melting component (Al) at the temperature of W dissolution in liquid Al in a melting furnace. Thus, to prevent evaporation, ligatures should be made, which will then be introduced during the preparation of the structural alloy. Methods. Microscopic analysis of samples on a light microscope (Jenaphot 2000 by Carl Zeiss) and a scanning electron microscope (SEM 106I by Selmi) and X-ray phase analysis (Rigaku Ultima IV). Main results. It is shown that the atomic dissolution of W in liquid Al is preceded by Rebinder’s enrichment of intergranular boundaries of W with Al, forming an intermediate ε- or ζ- phase and subsequent rafting of the W crystal in the liquid phase. Similarly, dendritic crystals of ε- and other intermediate phases that formed during the interaction of W and liquid Al through a cascade of peritectic reactions are dissolved. Conclusions. 1.The direct dissolution of W in liquid Al at1300 °C is either absent or marginally small. 2.The reaction between liquid Al and W involves the intense diffusion of Al atoms along the grain boundaries and sub-boundaries. This results in the formation of layers of an intermetallic phase ε (T<1300 °C) or ζ (T>1300 °C). The formation of two interfaces of the intermetallic phase (ε/L and ε/W or ζ /L and ζ /W) leads to diffusion of Al atoms from liquid Al through the intermetallic phase to W. 3.The saturation of the ε-phase with Al at the ε/W interface and the ζ-phase at the ζ /W interface causes them to melt and fragment the W. This fragmentation increases the speed of peritectic melting of W, improves the macroscopic homogeneity of the ligature alloy, reduces high-temperature evaporation of Al, and reduces energy costs for the technological process.

Keywords
peritictic, melting, tungsten, interdiffusion, aluminium

Acknowledgments
Not provided

References
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