Deformation Behavior in Nano-Polycrystalline Zirconium

M. RUDA; C. J. RUESTES; G. BERTOLINO; D. FARKAS; E. M. BRINGA

San Antonio, TEXAS

Congreso; TMS; 2013

TMS

We present atomistic simulations of stress-strain curves of nano-polycrystalline hcp Zr under uniaxial tension, using molecular dynamics (MD) and embedded atom method (EAM) potentials. The simulation blocks consisted of columnar grains rotated randomly with respect to each other about the [0001] axis; the grain boundaries were all pure tilt with random misorientation angles. For grain sizes smaller than a critical size, the average flow stress of nano-polycrystalline hcp Zr decreased with decreasing grain size. The opposite was true for grains larger than the critical size, 17-25 nm depending on the strain rate. The Young modulus was larger with increasing grain size. Decreasing the strain rate by a factor of 5 lowered the average flow stress, especially for larger grains. Increasing the temperature from 10 K to 300 K lowered the flow stress significantly. Deformation mechanisms such as dislocations, twinning and grain boundary sliding were affected by the grain size.