Monitoring microstructure evolution of nickel at high temperature

Laser ultrasonics is used to monitor the microstructure evolution of commercial pure nickel from room temperature up to 1000 \ub0C. The objective is to characterize the response of ultrasonic velocity, attenuation and absorption to recovery/recrystallization and grain growth. These parameters are measured during the applied thermal cycle and for different magnetic fields. Below the Curie temperature, the annealed microstructure shows strong magnetoelastic effects. Above the Curie temperature, the ultrasonic attenuation is dominated by grain scattering, allowing the characterization of grain growth. A relationship between the grain size and attenuation at high temperatures is established.Peer reviewed: YesNRC publication: Ye