Strain-rate sensitivity of strength in macro-to-micro-to-nano crystalline nickel

[摘要] The mechanical behavior of nickel is evaluated over eight-orders of magnitude change in strain rate to see if the change in strain-rate sensitivity exponent is affected by the grain size decreasing from the micron to nanoscale range. Tensile testing is used to measure the strain-rate dependence of the tensile strength on the grain size in crystalline nickel foils. Micro-scratch testing is used to determine the strain-rate dependence of the scratch hardness variation with scratch velocity. It is found that the mechanical test results can be directly compared. The increase in the strain-rate sensitivity exponent that is found with increasing strain rate is slower for nanocrystalline than for microcrystalline nickel foils where strength values begin to converge at the highest strain rates. (C) 2011 Elsevier B.V. All rights reserved.

[发布日期] 2011-12-25

[关键词] Nickel;Nanocrystalline;Tensile testing;Strain rate sensitivity;Scratch hardness;Electrodeposited coatings