Copper-based high strength nanofilamentary wires reinforced by bcc
nanofilaments (Nb or Ta) are prepared by severe plastic deformation for the
winding of high pulsed magnets. In-situ tensile tests under neutron beam
were performed on a Cu/Nb nanocomposite composed of a multiscale Cu matrix
embedding 554 Nb filaments with a diameter of 267 nm and spacing
of 45 nm. The evolution of elastic strains for individual lattice plane in
each phase and peak profiles in the copper matrix versus applied stress
evidenced the co-deformation behavior with different elastic-plastic regimes
and load sharing: the Cu matrix exhibits size effect in the finest channels
while the Nb nanowhiskers remain elastic up to the macroscopic failure, with
a strong load transfer from the copper matrix onto zones that are still in
the elastic regime. Taking into account results from residual lattice
strains also determined by neutron diffraction, the yield stress in the
finest Cu channels is in agreement with calculations based on a single
dislocation regime.