Starting niobium samples with different oxygen contents were produced by arc melting and electron beam melting respectively.The equilibrium oxygen contents of the niobium metal have been measured in the temperature range of 1173-1473K for Ca CaO Nb and of 973 and1173K for Mg MgO Nb by an inert gas fusion infrared absorption method.The equilibrium oxygen contents in Nb increases with temperature,which is independent of oxygen concentration of the starting Nb samples.Based on the equilibrium oxygen conte...