A Rapidly Degradable Extruded Mg-Y-Zn-Ni Alloy for Fracturing Tool Applications

Microstructure evolution, mechanical properties, and degradation behavior of a rapidly degradable extruded Mg-2Y-0.5Zn-0.5Ni (at%) alloy for fracturing tool applications are investigated. The microstructure of the extruded alloy is mainly composed of a recrystallization region and a nonrecrystallization region, in which the 18 R-long-period stacking order (LPSO) phase with two kinds of morphologies are distributed along extrusion direction. Parts of 18R-LPSO phase transfer into 14 H-LPSO phase during extrusion. A small amount of 14H-LPSO phases precipitate in the alpha-Mg matrix. The extruded alloy exhibits good mechanical properties, the ultimate tensile strength, tensile yield strength, and ultimate compressive stress of the extruded alloy are 364, 316, and 389 MPa, which increase by 97.5%, 334%, and 32.8% as compared with that of the as-cast alloy, respectively, which are attributed to grain refinement, LPSO phase strengthening, and texture strengthening. More importantly, the immersion and electronic chemical tests indicate that the extruded alloy has a high degradation rate (17.5 mg cm(-2)h(-1)). The rapid degradation rate of the extruded alloy is mainly due to the introduction of a significant number of defects especially for the microgalvanic corrosion between the LPSO phase and the alpha-Mg matrix.