Fig. 1 Microstructures of the as-cast RHEA: a XRD pattern; b and c SEM images; d BSE image and EDS maps

Fig. 2 a EBSD IPF (the inset shows grain size distribution); b phase map; c and d dark-field (DF) TEM image and corresponding SAED pattern

Fig. 3 Mechanical properties of as-cast RHEA. a Compressive engineering/true stress-strain curves at RT; b strain hardening rate curve; c comparison of the mechanical properties in the present work with references at RT [11,26,27,28,29,30,31]; d compressive true stress-strain curves at high temperatures; e and f comparison of the mechanical properties in the present work with references at high temperatures [11,12,28,29,32,33,34,35,36,37,38,39]

Fig. 4 a SEM image of the as-cast RHEA after 20% compression; b magnified image corresponding to a; c the IPF map and d the KAM map of the as-cast RHEA after 20% compression

Fig. 5 Two-beam condition bright field (BF)-TEM image of the as-cast RHEA with different g vectors along Z = [−111] after 50% compression at RT

Fig. 6 EBSD IPF and grain boundary (GB) maps of the microstructures of the as-cast RHEA sample after 50% compression different temperatures. a and d 800 °C, b and e 1000 °C, c and f 1200 °C. In the GB maps, low-angle boundaries (2°-10°) are drawn in red, and high-angle boundaries (> 10°) are drawn in black

Fig. 7 a BF-TEM image and b two-beam condition BF-TEM image with g = (101) of the as-cast RHEA sample after 20% compression at RT

Fig. 8 Two-beam condition BF-TEM image with different g vectors along Z = [−111] of the as-cast RHEA after 50% compression at 800 °C

Fig. 9 Two-beam condition BF-TEM image with different g vectors along Z = [−111] of the as-cast RHEA after 50% compression at 1200 °C

Fig. 10 Local misorientation (LM) map of the as-cast RHEA after 50% compression at different temperatures: a 800 °C, c 1200 °C; distributions of GND density under different compression temperatures: b 800 °C, d 1200 °C