The activity of oxygen in melts of nickel containing boron and hafnium, at PAr = 0.1 MPa

V. T. Burtsev.

ABSTRACT

Deoxidizing of heat-resistant nickel-based alloys during vacuum melting is carried out in the presence of aluminum strong deoxidizers boron and hafnium, which requires additional knowledge about the activity of dissolved oxygen. For this purpose, we studied a_[O] in model melts Ni–O–B/Hf (0.001–0.1% wt. % of each) and Ni–O–Al (5%) – B/Hf (0.001–0.1% of mass) at 1560^оС and P_Ar = 0.1 MPa by the method of instantaneous recording of the EDS using certified sensors. It was shown that for the melts Ni–O–(B/Hf), the dependences a_[O] = f [B/Hf] are described by logarithmic functions and at 0.05% of the deoxidizer a_[O] with the introduction of B is 1.1 times less than Hf, and for the melts Ni–O–Al (5%) –B/Hf (0.05% of each) a_[O] with the introduction of B decreased by 1.5 times compared to Hf, what determines the order of introduction of deoxidizers and its number, preferring B as the final deoxidizer.

KEYWORDS:

melts nickel-oxygen, boron, hafnium, EMF method, deoxidation.

DOI: 10.31857/S0235010620040039