THE EFFECTS OF STRESS STATE AND HYDROGEN PERMEATION ON HE FRACTURE OF AMORPHOUS NiCrFeSiB ALLOY
应力状态和渗氢条件在非晶态NiCrFeSiB合金氢脆断裂中的作用

Hydrogen embrittlement fracture of amorphous NiCrFeSiB alloy has been investigated by constant extension rate testing after electrochemical charging. Under weak hydrogen charging condition, fracture was controlled mainly by stress state of the sample. If hydrogen permeation was strengthened, a hydrogen concentration gradient was set up and a "river" pattern on the fracture surface was observed which indicates the gradually increased plastic deformation from the surface to the inner of the sample before fracture. Under strong hydrogen charging condition,hydrogen content near the surface was high and its concentration gradient was very steep, leading to "cleavage" fracture near the surfaces and "ductile" fracture in the core region of the sample. The fracture models based on the effect of hydrogen on the degree of localized plastic deformation are proposed.