Development of a Technology of Production of a Hafnium–Nickel Master Alloy in a Vacuum Arc Furnace for the Alloying of Cast Nickel Superalloys

A technology of producing a high-quality hafnium–nickel GfNi10 master alloy is developed: it is produced in a vacuum arc furnace with a nonconsumable electrode using a preliminary annealed pressed electrolytic hafnium powder. The total content of impurities and oxygen and nitrogen gases in the master alloy is found to be substantially lower than that in a serial GFN-10 master alloy. The character of interaction of the master alloy with the nickel melt during vacuum induction melting of the new VZhM200 cast nickel superalloy shows that, in contrast to a GFN-10 master alloy, the GfNi10 master alloy produced in VIAM gives no melt splashes during the introduction of the master alloy; this increases the assimilation of hafnium. The chemical composition and mechanical properties of a serial VKNA-1VR alloy and the new VZhL125 nickel superalloy melted with the developed master alloy correspond to the requirements of specifications for these alloys. In addition, high hafnium assimilation and low contents of gas impurities are ensured.