In the present study, low energy ion implantation was employed to engineer the surface of a Zr-ba... more In the present study, low energy ion implantation was employed to engineer the surface of a Zr-based bulk metallic glass (BMG), aiming at improving the biocompatibility and imparting bioactivity to the surface. Ca-or Ar-ions were implanted at 10 or 50 keV at a fluence of 8 × 10 15 ions/cm 2 to (Zr 0.55 Al 0.10 Ni 0.05 Cu 0.30) 99 Y 1 (at.%) BMG. The effects of ion implantation on materials properties and subsequent cellular responses were investigated. Both Ar-and Ca-ion implantations were suggested to induce atom displacements on the surfaces according to the Monte-Carlo simulation. The change of atomic environment of Zr in the surface regions as implied by the alteration in X-ray absorption measurements at Zr K-edge. X-ray photoelectron spectroscopy revealed that the ion implantation process has modified the surface chemical compositions and indicated the presence of Ca after Ca-ion implantation. The surface nanohardness has been enhanced by implantation of either ion species, with Ca-ion implantation showing more prominent effect. The BMG surfaces were altered to be more hydrophobic after ion implantation, which can be attributed to the reduced amount of hydroxyl groups on the implanted surfaces. Higher numbers of adherent cells were found on Ar-and Ca-ion implanted samples, while more pronounced cell adhesion were observed on Ca-ion implanted substrates. The low energy ion implantation resulted in concurrent modification in atomic structure, nanohardness, surface chemistry, hydrophobicity, and cell behavior on the surface of the Zr-based BMG, which were proposed to be mutually correlated with each other.
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2012
Zr‐based bulk metallic glasses (BMGs) possess attractive properties for prospective biomedical ap... more Zr‐based bulk metallic glasses (BMGs) possess attractive properties for prospective biomedical applications. The present study designs Ni‐free Zr–Cu–Al–Nb–Pd BMGs and investigates their in vitro biocompatibility by studying mechanical properties, bio‐corrosion resistance, and cellular responses. The Ti–6Al–4V alloy is used as a reference material. It is found that the Zr‐based BMGs exhibit good mechanical properties, including high strengths above 1600 MPa, high hardness over 4700 MPa, and low elastic moduli of 85–90 GPa. The Zr‐based BMGs are corrosion resistant in a simulated body environment, as revealed by wide passive regions, low passive current densities, and high pitting overpotentials. The formation of ZrO2‐rich surface passive films of the Zr‐based BMGs contributes to their high corrosion resistance, whereas their pitting corrosion in the phosphate buffered saline solution can be attributed to the sensitivity of the ZrO2 films to the chloride ion. The general biosafety of ...
The effects of metallurgical factors on the aqueous corrosion behavior of highentropy alloys (HEA... more The effects of metallurgical factors on the aqueous corrosion behavior of highentropy alloys (HEAs) are reviewed in this article. Alloying (e.g., Al and Cu) and processing (e.g., heat treatments) effects on the aqueous corrosion behavior of HEAs, including passive film formation, galvanic corrosion, and pitting corrosion, are discussed in detail. Corrosion rates of HEAs are calculated using electrochemical measurements and the weight-loss method. Available experimental corrosion data of HEAs in two common solutions [sulfuric acid (0.5 M H 2 SO 4) and salt water (3.5 weight percent, wt.%, NaCl)], such as the corrosion potential (E corr), corrosion current density (i corr), pitting potential (E pit), and passive region (ΔE), are summarized and compared with conventional corrosionresistant alloys. Possible directions of future work on the corrosion behavior of HEAs are suggested.
The deformation dynamics and the effect of deformation history on plastic deformation in a wrough... more The deformation dynamics and the effect of deformation history on plastic deformation in a wrought magnesium alloy at room temperature have been studied by real-time in situ neutron diffraction measurements under a continuous loading condition. The experimental results reveal that no detwinning occurred during unloading after compression and even in an elastic region during reverse tension. It is found that the serration behavior is closely related to the twinning-and detwinning-dominated deformation.
In the present study, low energy ion implantation was employed to engineer the surface of a Zr-ba... more In the present study, low energy ion implantation was employed to engineer the surface of a Zr-based bulk metallic glass (BMG), aiming at improving the biocompatibility and imparting bioactivity to the surface. Ca-or Ar-ions were implanted at 10 or 50 keV at a fluence of 8 × 10 15 ions/cm 2 to (Zr 0.55 Al 0.10 Ni 0.05 Cu 0.30) 99 Y 1 (at.%) BMG. The effects of ion implantation on materials properties and subsequent cellular responses were investigated. Both Ar-and Ca-ion implantations were suggested to induce atom displacements on the surfaces according to the Monte-Carlo simulation. The change of atomic environment of Zr in the surface regions as implied by the alteration in X-ray absorption measurements at Zr K-edge. X-ray photoelectron spectroscopy revealed that the ion implantation process has modified the surface chemical compositions and indicated the presence of Ca after Ca-ion implantation. The surface nanohardness has been enhanced by implantation of either ion species, with Ca-ion implantation showing more prominent effect. The BMG surfaces were altered to be more hydrophobic after ion implantation, which can be attributed to the reduced amount of hydroxyl groups on the implanted surfaces. Higher numbers of adherent cells were found on Ar-and Ca-ion implanted samples, while more pronounced cell adhesion were observed on Ca-ion implanted substrates. The low energy ion implantation resulted in concurrent modification in atomic structure, nanohardness, surface chemistry, hydrophobicity, and cell behavior on the surface of the Zr-based BMG, which were proposed to be mutually correlated with each other.
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2012
Zr‐based bulk metallic glasses (BMGs) possess attractive properties for prospective biomedical ap... more Zr‐based bulk metallic glasses (BMGs) possess attractive properties for prospective biomedical applications. The present study designs Ni‐free Zr–Cu–Al–Nb–Pd BMGs and investigates their in vitro biocompatibility by studying mechanical properties, bio‐corrosion resistance, and cellular responses. The Ti–6Al–4V alloy is used as a reference material. It is found that the Zr‐based BMGs exhibit good mechanical properties, including high strengths above 1600 MPa, high hardness over 4700 MPa, and low elastic moduli of 85–90 GPa. The Zr‐based BMGs are corrosion resistant in a simulated body environment, as revealed by wide passive regions, low passive current densities, and high pitting overpotentials. The formation of ZrO2‐rich surface passive films of the Zr‐based BMGs contributes to their high corrosion resistance, whereas their pitting corrosion in the phosphate buffered saline solution can be attributed to the sensitivity of the ZrO2 films to the chloride ion. The general biosafety of ...
The effects of metallurgical factors on the aqueous corrosion behavior of highentropy alloys (HEA... more The effects of metallurgical factors on the aqueous corrosion behavior of highentropy alloys (HEAs) are reviewed in this article. Alloying (e.g., Al and Cu) and processing (e.g., heat treatments) effects on the aqueous corrosion behavior of HEAs, including passive film formation, galvanic corrosion, and pitting corrosion, are discussed in detail. Corrosion rates of HEAs are calculated using electrochemical measurements and the weight-loss method. Available experimental corrosion data of HEAs in two common solutions [sulfuric acid (0.5 M H 2 SO 4) and salt water (3.5 weight percent, wt.%, NaCl)], such as the corrosion potential (E corr), corrosion current density (i corr), pitting potential (E pit), and passive region (ΔE), are summarized and compared with conventional corrosionresistant alloys. Possible directions of future work on the corrosion behavior of HEAs are suggested.
The deformation dynamics and the effect of deformation history on plastic deformation in a wrough... more The deformation dynamics and the effect of deformation history on plastic deformation in a wrought magnesium alloy at room temperature have been studied by real-time in situ neutron diffraction measurements under a continuous loading condition. The experimental results reveal that no detwinning occurred during unloading after compression and even in an elastic region during reverse tension. It is found that the serration behavior is closely related to the twinning-and detwinning-dominated deformation.
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