Thermodynamic analysis of the oxidation behaviour of lanthanum in GH4169 alloy during electroslag remelting

To reduce the lanthanum loss in La-containing GH4169 during electroslag process, the thermodynamic of lanthanum oxidation was investigated based on slag-steel reaction experiments and thermodynamic calculation. The results show that lanthanum in the alloy can react with Al 2 O 3 and TiO 2 in the slag, resulting in the loss of lanthanum in the alloy. With the increase of Al 2 O 3 content in the slag from 18.41 wt-% to 24.73 wt-%, the yield of lanthanum decreased from 12.1% to 7.9%. When the La 2 O 3 content in the slag increased from 3.99 wt-% to 10.14 wt-%, the yield of lanthanum in the alloy increased from 7.9% to 18.7%. With the increase of CaF 2 , Al 2 O 3 and TiO 2 contents in the slag, the activity of La 2 O 3 decreases, which is in favour of lanthanum loss in the alloy. The activity of La 2 O 3 increases with the increase of CaO, La 2 O 3 and MgO content in the slag, which would restrain the loss of lanthanum in the alloy during electroslag remelting process.