Dislocation relaxation spectra in plastically deformed refractory b.c.c. metals

Progress and problems in the understanding of the dislocation relaxation processes in metals

“…versus the ␤-peak temperatures T p as observed by Mühlbach [97] on an ultra-pure Mo crystal (RRR ≈ 3 × 10 5 ; same provenance as the starting material of Hollang et al [67,78]) and by Suzuki [98] in torsion-pendulum measurements on a 1 1 2 -oriented high-purity Mo crystal (RRR ≈ 2.5 × 10 4 ) are compared with the Chambers-Schultz [57] ␤-relaxation data on less pure polycrystalline Mo (RRR = 57, main impurities O and N). 19 The data may be described by Eq.…”

“…A few years after the mechanism of the Bordoni-type relaxation processes in fcc metals had become the subject of discussion, a search for analogous processes in bcc metals began [52][53][54][55][56][57][58]. By that time, striking differences between the deformation behaviour of fcc and bcc metals were already well established.…”

“…Chambers and Schultz [57,68] classified the relaxation phenomena detected in the early internal-friction measurements on plastically deformed bcc metals, in the sequence of increasing peak temperatures T p , as ␣-, ␤-, and ␥-relaxation. This classification is still very useful and will serve as guideline for the following discussion.…”

Single-kink relaxation processes in iron–chromium binary alloys

“…They are observed in the internal friction spectra of both fcc and bcc metals; for a recent review see [11]. These peaks, usually referred to in the literature as Niblett-Wilks (NW) peaks in fcc [12], and aš -peaks in bcc [13] metals, also appear under plastic deformation and decrease upon annealing, indicating close relationship with the relaxation process due to the kink-pair generation. However, there is a dispute in the literature about the activation mechanism responsible for these relaxation processes.…”

Verhakungen, dislocations, solitons, and kinks

“…In several bcc metals, such processes were subsequently detected by Chambers and Schultz [73 -76] and classified, in a sequence of increasing temperatures, as a-, b-, and c-relaxation [75,76], with a later subdivision of the original a-relaxation into a and a 0 . 14 A critical test of the correctness of the writer's suggestion [49] was the existence of a relaxation process that is caused by the kink-pair generation in a 0 <111>/2 screw dislocations, since it is these dislocations whose large Peierls barriers are generally held responsible for the strong temperature and strain-rate dependence of the flow stress of bcc transition metals (see, e. g., [64]).…”