The effect of size, orientation and temperature on the deformation of microcast silver crystals

Monocrystalline microwires of silver are produced by means of a novel casting process that combines precise mold production by silicon microfabrication with molten metal pressure infiltration. The wires have a shape amenable to tensile testing and a diameter from a few to several tens of micrometer. Displacement-controlled in -situ tensile tests are conducted at room-temperature, 200 degrees C and 400 degrees C. Data are compared with bulk coun-terparts of the same silver cast to have a diameter near 1 mm. Results show clear evidence of small-scale plasticity. The influence of size, crystal orientation, and temperature on the deformation, yield, strain burst statistics and strain hardening of these micrometric dense metal samples is analyzed. Yield stress values agree with the single arm source model provided that the density of forest dislocations comprises a scale-dependent component likely resulting from thermal mismatch stresses. Statistics of strain burst amplitudes agree with an exponentially truncated power-law complementary cumulative distribution. The power-law exponent agrees with predictions of mean-field theory, while the cutoff intensity exhibits no visible dependence on sample diameter or test temperature and agrees with predictions of current theory.