Competitive growth of eutectics in chromium-tungsten white cast irons

Unidirectional solidification was carried out to investigate solidification sequences of the eutectics in hypoeutectic chromium-tungsten white cast irons containing 8-17 mass % Cr, 2.7-3.2 mass % C and 5 mass % W at the growth rate of 0.003 to 0.4 mm/s. At lower growth rates, gamma+M7C3 eutectic crystallized before g+M3C eutectic, At higher growth rates, gamma+M3C eutectic crystallized preferentially and no gamma+M7C3 eutectic crystallized. The interface temperatures of primary austenite and both eutectics were measured as a function of growth rate and the criterion phase selection was successfully applied to explain the experimental results.