Comprehensive Microstructural Characterization of γ′ in a Nimonic Alloy Using Ultrasonic Velocity Measurements

Microstructure of a crystalline material is a key factor in its technological applications as it determines a wide variety of properties including mechanical strength, toughness, corrosion resistance, and hardness. In Nimonic alloys, precipitation takes place during processing and on prolonged exposure to service at elevated temperatures. Consequently, knowledge about the precipitation phases and their influence on the various properties is of fundamental interest not only for its intrinsic study but also for its technological significance. The purpose of the present study is to explore the possibility of using ultrasonic velocity measurement in a Nimonic alloy and characterize the precipitation behavior on aging. It is concluded from this study that ultrasonic velocity is more sensitive than the conventional microstructural sensitive parameter like hardness due to its dependence on the chemical compositional variations.