Strong cooperation growth of two phases in the ternary eutectic

The growth mechanism and tensile performance of ternary Ni_40.6Fe_36.4Ti₂₃ alloy were investigated using directional solidification technique. The ternary Fe₂Ti+γ-Fe(Ni)+Ni₃Ti eutectic formed a lamellar structure under the steady state growth. After quenching, the Fe₂Ti phase transformed into independently grown fiber while the γ-Fe(Ni) and Ni₃Ti phases kept lamellar structure. It was confirmed that the solid/solid interfacial energy anisotropy contributed to the strong cooperation growth of the two phases in the ternary eutectic. The γ-Fe(Ni)/Ni₃Ti interface preferred to be parallel to the common planes of {111}_γ and {0001}_Ni3Ti with low interfacial energy, leading to the formation of the stable lamellar structure under different solidification conditions. Owing to the reduction of transverse grain boundaries and grain refinement, the alloy solidified at 10 μm/s growth velocity showed the highest tensile strength and Young's modulus with translamellar fracture mechanism.