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ASET Colloquium

In-Situ Ultrasonic Materials Characterisation at Elevated Temperatures

by Prof. Sakthipandi Kathiresan (Department of Physics, SRM TRP Engineering College, Tiruchirappalli)

Friday, October 1, 2021 from to (Asia/Kolkata)
at Online ( https://zoom.us/j/91427966752 )
Description Ultrasonic nondestructive evaluation (NDE) technique is a versatile and sensitive tool for structural/microstructural and defect characterisation of materials. An indigenous experimental set-up for in-situ measurement of ultrasonic velocities and attenuation at high temperatures has been designed and fabricated. The set-up can be used for ultrasonic measurements in the solid materials over a wide range of temperatures from room temperature (298 K) to 1200 K. The set-up has the facilities to vary the sample temperature in the static or dynamic mode of operation and is suitable for samples of different thicknesses. The measured ultrasonic parameters such as longitudinal and transverse velocities and attenuation are correlated to mechanical properties like elastic constants and microstructural features. In order to explore the precise information about the structural/phase transitions, first differentials of the temperature-dependent ultrasonic parameters have been explored. The developed experimental set-up has been validated through benchmark studies on a few materials with known phase/structural transitions. The ultrasonic attenuation and velocity measurements carried out in La0.67Sr0.33MnO3 perovskite in the temperature range of 290 to 470 K clearly identified the Curie temperature (TC) i.e., paramagnetic (PM) to ferromagnetic (FM) phase transition. In addition, measurements provided evidence for the existence of strong electron-phonon interactions, which arises due to the John-Teller effect, and the spin-phonon interactions due to the linear (single-ion) magnetostriction effect. Studies carried out on Al-Li alloy 8090 in the temperature range from 300 to 623 K clearly showed nucleation, growth, and dissolution of GP zones, δ, δ′ and S′ precipitates. It is observed that the first differential plots of variation in ultrasonic velocity with temperature are more effective in predicting the temperatures at which the structural changes take place. In-situ high-temperature ultrasonic studies made on β-quenched Zircaloy-2 specimens revealed the formation of intermetallic precipitates from the martensite phase.

About the Speaker:
Dr. Sakthipandi Kathiresan obtained his Ph.D. in Physics from Anna University in 2013. Before joining SRM TRP Engineering College, he held academic positions at Erode Arts and Science College, K. S. Rangasamy College of Technology, Sethu Institute of Technology, and IISc, Bengaluru. He published 80 journals papers, co-authored three research books, and guided six doctoral students. He won several awards and fellowships for his outstanding research throughput. These include the INSA Research Scientist Award, Tamil Nadu State Council for Science and Technology Young Scientist Fellowship, JNCASR Visiting Fellowship, CSIR Senior Research Fellowship, Acoustical Society of America International Student Grant Fellowship, Sir CV Raman Award for Best Physics Teacher in Engineering College from SEEE, Dr. TK Saxsena Memorial Award from Ultrasonic Society of India, and so on.
Organised by Dr. Satyanarayana Bheesette