Directional Solidification of (Ti, Zr) Carbide‐(Ti, Zr) Diboride Eutectics

Abstract

Crystallographic and microstructural features of the directionally solidified ZrC‐ZrB 2 , ZrC‐TiB 2 , and TiC‐TiB 2 eutectics were studied. Growth directions were the [011] for the cubic carbide phases and the [01.0] for the hexagonal diborides, yielding an interfacial plane for the lamellar eutectics of (111) cubic parallel to (00.1) hexagonal . The ZrC‐ZrB 2 and TiC‐TiB 2 each exhibited regular lamellar growth, whereas the ZrC‐TiB 2 had a Chinese script‐type of microstructure. A λ 2 R= constant growth law was followed where the constants are (2.57 plusmn; 0.63) × 10 ‐18 m 3 /s for the ZrC‐ZrB 2 , (3.97 ± 0.60) × 10 −18 m 3 /s for the TiC‐TiB 2 , and (2.74 ± 0.68) ± 10 ‐17 m 3 /s for the ZrC‐TiB 2 .