Prof.  Mahesh K.  K.
Nagarjuna College of Engineering and Technology,  India

Title: Exploring R-phase transformation in Ni-Ti shape memory alloys

Abstract:

It is known that the shape memory effect (SME) exhibited by certain alloys is due to the crystallographic phase transformation. The change in temperature or stress are the driving force for the phase transformations. Equiatomic Nickel-Titanium (Ni-Ti) alloys are well known for their superior shape memory properties. In Ni-Ti shape memory alloys (SMAs), the high temperature phase is known as austenite (A) having B2 structure and the low temperature phase is known as martensite (M) phase having monoclinic structure. In special cases, there exists an intermediate phase known as, R-phase (R) having rhombohedral structure during the AM phase transformation. It is also interesting to note that R-phase transformation is prominent during the A->M phase transformation. Hence, R-phase transformation is widely studied during the AR transformation. The major differences between the presence or absence of R-phase transformation in between A and M phases are the temperature interval and the thermal hysteresis involved. R-phase transformation takes place in a narrow temperature interval involving smaller thermal hysteresis. These features are preferred in various devices. The present talk highlights the progress in understanding R-Phase transformation, its potential applications and certain research gaps to be addressed.

Biography:

Dr. Mahesh K.K. holds Ph.D. in Materials Science from Mangalore University, India. He has post-doctoral research experience at CENIMAT (Materials Research Centre), Universidade Nova de Lisboa, Portugal. His research interests broadly involve Materials Science, Physical Metallurgy and X-ray crystallography. In specific, he is involved in the characterization (thermal, electrical, mechanical and structural) of shape memory alloys and investigating their phase transformations. He has participated in the collaborative experimental sessions at Synchrotron facilities for in-situ analyses of Ni-Ti SMAs at ESRF, France and DESY-HASYLAB, Germany. So far, Dr. Mahesh has publications of more than 70 peer reviewed research papers and participated in more than 40 international conferences. He is a reviewer to several journals of Elsevier, IOPscience and Trans Tech Publications. He has caried out one research project as Principal Investigator and 4 as Co-investigator in the field of Ni-Ti shape memory alloys. At present, he is a Professor of Physics at Nagarjuna College of Engineering and Technology, Bangalore, India.