Fig. 1. The received Mo-3Nb single crystal bar (a); the region and direction of sampling (b); the crystallographic orientations for single crystal specimens before compression(c) and corresponding inverse pole figure map (d).

Fig. 2. The true stress-strain curve of compressed Mo-3Nb single crystal (a) and corresponding strain hardening rate curve (b).

Fig. 3. Slip traces of Mo-3Nb single crystal compressed at ε=4% (a-c), 7% (d-f), 15% (g-i), 30% (j-l) and 50% (m-o). Face A (a, d, g, j, m) represents the front surface (green) and Face B (b, e, h, k, n) represents the side surface (orange); (c, f, i, l, o) are AFM morphologies for Face B.

Fig. 4. The curve demonstrating the horizontal and vertical distances variation for slip steps at different strains.

Fig. 5. Dislocation arrangements of Mo-3Nb single crystal compressed at various strain hardening stages: stage I (a-c); stage II (d-f); softening stage (g-l). The thin foils were sectioned parallel to (101) plane.

Fig. 6. Schematic diagram showing the different slip traces induced by double cross-slip multiplication mechanism: screw dislocation glides on primary (101) plane (a); small segments of a gliding screw dislocation cross slip onto secondary slip plane (b); the dislocation in secondary slip plane cross slip again onto a parallel (101) plane and the formation of dislocation jog (c); the loop generated by dislocation multiplication (d) and slip traces formed by repeating the process of double cross-slip multiplication (e).