Yield and Stage I Deformation of Neutron-Irradiated Copper Crystal in Connection with Formation of Slip Bands

抄録

A neutron-irradiated copper crystal (φ=1×10²² n·m⁻², E>0.1 MeV) has been elongated at room temperature to investigate pre- and post-yield deformation and work-hardening in stage I deformation in connection with the formation of primary and secondary slip bands using an etch-pit technique. Main results are as follows:
(1) Individual deformation stages of a stress (τ)-strain(γ) curve just corresponds with individual stages of a N_p-γ curve, where N_p is the number of the primary slip traces.
(2) The primary slip begins to appear at the multiplication stress (τ_m) much less than the upper yield stress (τ_uy), and τ_m is about 70% of τ_uy.
(3) The spacing of the primary slip traces and the shear displacement in them decrease in yield deformation with increasing strain, but they are constant in stage I independently of strain.
(4) The mobility of edge dislocations is surely larger than that of screw ones.
(5) The secondary slip begins to grow from a definite side of the clusters of the primary slip traces towards undeformed matrices.
(6) There is a surface effect in the formation of the secondary slip bands.
From these results, the mechanism of pre- and post-yield deformation, the work-hardening in stage I deformation and heterogeneous formation of the secondary slip bands are discussed.