The equiatomic Co-Cr-Fe-Mn-Ni high-entropy alloy (HEA) shows well hydrogen embrittlement resistance under monotonic tensile load. However, the fracture behavior under cyclic load is still unclear. In this study, combining with the fracture features analysis by electron back-scattered diffraction and electron channeling contrast imaging techniques, the hydrogen-assisted fatigue crack propagation behavior of equiatomic Co-Cr-Fe-Mn-Ni HEA under in situ electrochemical hydrogen charging was investigated. The results suggest that the hydrogen had significant accelerating effects on the fatigue crack growth rate of Co-Cr-Fe-Mn-Ni HEA. Intergranular cracking with the formation of dislocation cells was observed at low stress intensity range (ΔK) area, while transgranular cracking with deformation twins was observed at a high ΔK area. The formation of these deformation features was assisted by hydrogen-assisted dislocation emission.

To find the inner relations of extrusion key parameters, 2-factor and 3-level orthogonal experiments are carried out on the twin-screw extruder with the corn-rice powder as the materials. The factors are: screw rate and feed rate; the indices are: inner pressure, die outlet temperature and generator current. The results are analyzed by single index regression method, the results show that the screw rate has the significant influence on the variables of barrel inner pressure, die outlet temperature and generator current, while the feed rate only impact significantly on the barrel inner pressure and generator current. After the response analysis of the original variables, the desired experimental conditions are obtained. The parameters should be: screw rate=150rpm, feed rate=14rpm.