Microstructure, Mechanical Properties and Degradation Behavior of Extruded Mg-Y-Cu (Ni) Alloys for Fracturing Degradation Tools
摘要
The microstructure, mechanical properties and degradation behavior of the extruded Mg-2Y-1Cu (MYC, at.%) and Mg-2Y-0.5Cu-0.5Ni (MYCN, at.%) alloys were investigated in this study. The experimental results revealed that the addition of Ni effectively refined the grain size and modified the distribution and precipitation behavior of second phase in the extruded MYC alloy. The volume fraction of the long-period stacking ordered (LPSO) phases increased from 26.8% in the extruded MYC alloy to 39.9% in the extruded MYCN alloy. Tensile testing results indicated that the Ni addition enhanced the compressive strength from 332 MPa for the extruded MYC alloy to 351 MPa for the extruded MYCN alloy. Moreover, the immersion experiments and electrochemical tests indicated that the addition of Ni significantly increased the degradation rate, hydrogen evolution and weight loss rate of the extruded MYC alloy. The hydrogen evolution rate and weight loss rate of the extruded MYCN alloy were 21.985 ml/cm2·h and 23 mg/cm2·h, increased by 174% and 170% compared to those of the extruded MYC alloy, respectively. The enhanced degradation rate of the extruded MYCN alloy was mainly due to the significant galvanic corrosion between second phase and α-Mg matrix. Additionally, the high compressive strengths of the extruded MYCN alloy were mainly attributed to grain refinement and second phase strengthening resulting from LPSO phase.