Speaker: Dr. Punit Kumar
Lawrence Berkeley National Lab,
University of California, Berkeley, USA
Abstract:
Discovering structural materials that can withstand extreme environments is crucial, especially for aerospace, hypersonic, nuclear, and sustainable energy applications, for which these materials are required to be lightweight, withstand extreme temperatures (4 K-1873 K), and perform in corrosive environments. Historically, the selection and design of materials for these extreme environment applications has been challenging because of the conflict between their strength and fracture toughness. Broadly, the alloys with fee and be primary phases represent the opposite ends of the spectrum in this conflict of material’s damage tolerance. While fcc alloys show exceptional fracture toughness at room temperature and cryogenic temperatures, they have relatively lower resistance to plastic deformation; bee refractory alloys have excellent thermal stability and high compressive yield strength at temperatures above 1073 K but suffer from poor resistance to fracture in tension. This presentation will highlight the potential to overcome this strength-toughness trade-off using additive manufacturing and high entropy alloys. High entropy alloys are composed of elements mixed in high concentrations to form a primary single phase, which in some cases promotes combinations of deformation mechanisms, imparting fracture resistance to these materials. Meanwhile, additive manufacturing, a bottom-up process similar to how nature builds structures, can introduce hierarchical structures inside the materials to increase their strength without affecting fracture resistance.
Bio-data of the speaker:
Dr. Punit Kumar is a postdoc at the Lawrence Berkeley National Lab and the University of California, Berkeley. He received bachelor’s and master’s degrees in metallurgical and materials engineering from the National Institute of Technology, Rourkela, India. He did his Ph.D. thesis on the fracture and fatigue behavior of additively manufactured Tr-alloy at the Department of Materials Engineering, Indian Institute of Science, Bangalore, India. For the research work published during his Ph.D., he was awarded “The Acta Student Award 2019. As a postdoc at the School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, he investigated the mechanical properties of various conventional structural alloys produced by additive manufacturing processes such as laser powder bed fusion, directed energy deposition, binder jet printing, and electron beam melting. At the Lawrence Berkeley National Lab, he investigates the fracture behavior of high entropy alloy systems in extreme environments, ie, in the temperature range of 20 K to 1873 K. These high entropy alloys are produced by additive manufacturing and arc melting. Dr. Kumar was invited to give a keynote presentation at the “The Fracture Behavior of Additively Manufactured Alloys” symposium, International Conference on Fracture 2023, Atlanta, USA.
Organized by:
InSIS and Center for Structural Integrity of Safety Critical Systems, IIT Madras
