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Piyas Bal Chowdhury

• Advisor:
  • Huseyin Sehitoglu
• Departments:
  • Mechanical Science and Engineering
• Areas of Expertise:
  • Molecular dynamics
  • Density functional theory
  • Microstructure characterization
  • Shape memory alloys
  • Fracture, fatigue, deformation
• Thesis Title:
  • Modeling mechanical properties : linking atomistics to continuum
• Thesis abstract:
  
  • The microstructure-property correlation in metals and alloys has remained an important topic of research endeavors throughout the last century. Significant progresses were made in the 1950s through the early 1980s establishing important phenomenological laws. With the advent of major innovations in materials processing and testing, the last decade in particular has witnessed considerable developments in the knowledge of microplasticity that shape our modern understanding of microstructural influences on deformation response. For the current generation of scientists and researchers, advancement of novel alloys essentially requires delving deeper into an atomic level understanding of the structure–property relationship devoid of empiricism. Given the vast improvements in computational materials science tools, it is deemed timely and necessary to make major strides in establishing material laws informed by underlying atomic physics, free of empirical constants from a new perspective. To that end, we build on the foundation laid by the most contemporary knowledge of microplasticity at various lengthscales of relevant operative flow mechanisms. The current research emphasizes on a synergistic modeling approach, which bridges atomistic and mesoscale theories with experimental behavior. The topics that we cover is this thesis are: (a) fatigue crack growth in presence of coherent nano-sized twins, (b) strength of nanocrystalline NiCo alloys, (b) the competition between the slip and the twinning dominated deformation mechanisms and (d) superelasticity of NiTi shape memory alloys. We demonstrate that the macroscale mechanical attributes of the foregoing problems could most conveniently be predicted by considering the underlying atomic-scale physical phenomena such as various defect interactions and the associated energetics.
• Downloads:
  • Mechanical response of low stacking fault energy Co–Ni alloys–Continuum, mesoscopic and atomic level treatments
  • Modeling fatigue crack growth resistance of nanocrystalline alloys
  • Predicting fatigue resistance of nano-twinned materials Part I – Role of cyclic slip irreversibilities and Peierls stress
  • Predicting fatigue resistance of nano-twinned materials Part II – Effective threshold stress intensity factor range
  • Strength prediction in NiCo alloys - The role of composition and nanotwins

Contact information:
chowdhu2@illinois.edu