We constructed and developed an in-situ cryogenic nanomechanical system to study small-scale mechanical behavior of materials at low temperatures. Uniaxial compression of two body-centered-cubic （bcc） metals, Nb and...We constructed and developed an in-situ cryogenic nanomechanical system to study small-scale mechanical behavior of materials at low temperatures. Uniaxial compression of two body-centered-cubic （bcc） metals, Nb and W, with diameters between 400 and 1300 rim, was studied at room temperature and at 165 K. Experiments were conducted inside of a Scanning Electron Microscope （SEM） equipped with a nanomechanical module, with simultaneous cooling of sample and diamond tip. Stress-strain data at 165 K exhibited higher yield strengths and more extensive strain bursts on average, as compared to those at 298 K. We discuss these differences in the framework of nano-sized plasticity and intrinsic lattice resistance. Dislocation dynamics simulations with surface-controlled dislocation multiplication were used to gain insight into size and temperature effects on deformation of nano-sized bcc metals.展开更多
基金the financial support of the Kavli Nanoscience Institute (KNI) through LEE Seok-Woo’s prized post-doctoral fellowship, of the Keck Institute for Space Studies at Caltech, and of JRG’s NASA Early Career grantCHENG YinTong acknowledges the financial support of the Caltech SURF program
文摘We constructed and developed an in-situ cryogenic nanomechanical system to study small-scale mechanical behavior of materials at low temperatures. Uniaxial compression of two body-centered-cubic （bcc） metals, Nb and W, with diameters between 400 and 1300 rim, was studied at room temperature and at 165 K. Experiments were conducted inside of a Scanning Electron Microscope （SEM） equipped with a nanomechanical module, with simultaneous cooling of sample and diamond tip. Stress-strain data at 165 K exhibited higher yield strengths and more extensive strain bursts on average, as compared to those at 298 K. We discuss these differences in the framework of nano-sized plasticity and intrinsic lattice resistance. Dislocation dynamics simulations with surface-controlled dislocation multiplication were used to gain insight into size and temperature effects on deformation of nano-sized bcc metals.
