Effect of indium addition on microstructural, mechanical and oxidation properties of suction cast Nb–Si eutectic alloy

Abstract

The paper reports effect of small ternary addition of In on the microstructure, mechanical property and oxidation behaviour of a near eutectic suction cast Nb–19·1 at-%Si–1·5 at-%In alloy. The observed microstructure consists of a combination of two kinds of lamellar structure. They are metal–intermetallic combinations of Nb_ss–β-Nb₅Si₃ and Nb_ss–α-Nb₅Si₃ respectively having 40–60 nm lamellar spacings. The alloy gives compressive strength of 3 GPa and engineering strain of ∼3% at room temperature. The composite structure also exhibits a large improvement in oxidation resistance at high temperature (1000°C).

Keywords:

• Intermetallics
• Phase transformation
• Brittleness
• Ductility
• Casting
• Microscopy

The authors would like to thank the National Facility of Electron Microscopy at AFMM of IISc, Bangalore, for support. The financial support from the Department of Science and Technology is gratefully acknowledged.