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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 between400 and 1300 nm,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.
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 nm, 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 exhibits higher yield strengths and more strain bursts on average, as compared to the framework at 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.