Structural and electrochemical study of resorbable Ca32Mg12Zn38Yb18-xBx (x=1, 2, 3) metallic glasses in Ringer's solution

A new class of CaZn-based bulk glassy alloys with minor addition of boron and enhanced corrosion resistance for use in bioresorbable materials is introduced. The CaMgZnYbB alloys represent a new family of biomaterials with potential applications in orthopedic implants with controlled degradation rates and corrosion in the human body. The effect of substituting Yb for B in the structure on the corrosion and mechanical properties of quinternary Ca32Mg12Zn38Yb18-xBx (x = 1,2,3 at.%) alloys was investigated using X-ray diffraction, high-resolution transmission electron microscopy, differential scanning calorimetry, immersion and electrochemical polarization, compressive tests, and hardness measurements. The corrosion behavior was also evaluated using electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Microstructural investigations showed that the Ca32Mg12Zn38Yb16B2 alloy was mainly amorphous, while small reflections from nanocrystals were observed in Ca32Mg12Zn38Yb17B1 and Ca32Mg12Zn38Yb15B3. Electrochemical polarization and immersion tests in Ringer's solution at 37 °C revealed that the CaMgZnYbB alloys had significantly higher corrosion resistance than CaMgZn alloys. Electrochemical impedance spectroscopy of alloys showed only single capacitive loops. The corrosion products were identified as CaO, MgO, Mg(OH)2, and CaCO3. The compressive strengths of the alloys from 220 MPa to 283 MPa were suitable for implant applications.