Published online by Cambridge University Press: 01 January 1992
We have shown previously that directionally solidified β+γ-Ni70Al30 and β+(γ+γ)-Ni50Fe30Al20 alloys with quasi-lamellar microstructures exhibit up to 10% tensile ductility at 300 K. The ductility enhancement was partly attributed to a slip transfer mechanism which is favored by the Kurdjumov-Sachs orientation relationship and strong interphase interface that shows no debonding. The slip systems in the β phase were of the type {110}<001> even though the loading axis was parallel to the <001> growth direction in β. In the present investigation, an electron microscopy study of the β / γ and β / (γ + γ) interfaces has been conducted to understand the interfacial structure and its relation to room temperature mechanical properties. Furthermore, the stress concentration at the interface is treated analytically to understand how {110}<001> slip occurs in the β phase, even though the loading axis is along <001>.