Direct nucleation and growth of peritectic phase induced by substantial undercooling condition

Peritectic phase forms through peritectic transformation in most cases. Here we predicted theoretically a growth mechanism transition from peritectic transformation to the direct nucleation and growth of peritectic phase during rapid solidification. To demonstrate this experimentally, liquid Cu-Sn alloy was undercooled by up to 268 K (0.31T(L)). Once the undercooling exceeds a critical value of about 220 K, peritectic eta phase forms directly from the metastable liquid phase by suppressing the nucleation of primary epsilon phase and peritectic transformation. As undercooling increases in the range below 201 K, the primary epsilon phase is refined and peritectic transformation is promoted. (C) 2013 Elsevier B.V. All rights reserved.