TECHNOLOGICAL FEATURES OF MANUFACTURING ALLOY AK7h STRENGTHENED WITH ZIRCONIUM INTRODUCED WITH ZIRCONIUM TETRAFLUORIDE

Abstract

The paper considers the important features of the technology of strengthening AK7ch aluminum alloy with zirconium introduced with its tetrafluoride. The choice of a complex flux containing zirconium tetrafluoride in its composition is justified. It is indicated that in order to recover zirconium from its tetrafluoride in the aluminum melt, it is first of all necessary to ensure the formation of sodium or potassium fluorozirconate in the strengthening mixture. The mechanism of recovery of zirconium from tetrafluoride is presented. Technological recommendations for obtaining AK7ch alloy are given. It has been established that the complex flux intended to the alloy, which is modified, must be injected into liquid aluminum before the introduction of other alloying elements, namely silicon and magnesium. The maximum appropriate temperature for injecting zirconium into the aluminum melt from the complex flux is indicated. The maximum amount of zirconium that was recovered is 0.4%. The microstructure and mechanical properties of an alloy strengthened by zirconium from its tetrafluoride, which was injected into the alloy in the amount from 0.8 to 1.2%, were studied. As a result of the modification of aluminum alloy AK7ch with zirconium, the grains of silicon solution in aluminum (α-phase) are grind. No other structural changes are observed. The value of tensile strength and relative elongation of the alloy increases by 1.3 and 1.7 times, respectively.