Work-hardening of hexagonal Close-packed crystals and in the easy glide region of face-centred cubic crystals

In the present paper we collect the available evidence from work-hardening curves, slip-line observations, and ferromagnetic measurements on the easy glide region of f.c.c. metals and alloys and the low-temperature work-hardening of hexagonal metals. New experimental results are reported on copper single crystals deformed at liquid oxygen temperature. A dislocation theory of work-hardening is given which accounts rather well for the experimental facts. The work-hardening rate can be calculated from slip-line data (distances between and lengths of slip-lines) and is found to agree well with the measurements. The theory is a statistical one and is based on the fact that in the deformation stage considered here the important stress-fields are those of individual dislocations rather than those of piled-up groups. The present paper is another example for the usefulness of slip-line studies in theories of work-hardening.