Using Cu as a Spacer to Fabricate and Control the Porosity of Titanium Zirconium Based Bulk Metallic Glass Foams for Orthopedic Implant Applications

Abstract

In this study, a porous titanium zirconium (TiZr)-based bulk metallic foam was successfully fabricated using the Cu spacer by employing the hot press method. TiZr-based bulk metallic foams with porosities ranging from 0% to 50% were fabricated and analyzed. The results indicate that thermal conductivity increased with the addition of Cu spacer; the increased thermal conductivity reduced the holding time in the hot press method. Moreover, the compressive strength decreased from 1261 to 76 MPa when the porosity of the TiZr-based bulk metallic foam increased to 50%, and the compressive strength was predictable. In addition, the foam demonstrated favorable biocompatibility in cell viability, cell migration capacity, and calcium deposition tests. Moreover, the pore size of the porous TiZr-based bulk metallic foam was around 120 µm. In conclusion, TiZr-based bulk metallic foam has favorable biocompatibility, mechanical property controllability, and porous structure for bone ingrowth and subsequent enhanced osteointegration. This porous TiZr-based bulk metallic foam has great potential as an orthopedic implant to enhance bone healing and decrease healing time.

Keywords: Cu spacer; TiZr-based bulk metallic glass; biocompatibility; mechanical properties controllability; porous.

Figure 1

Thermal conductivity of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams fabricated using different volume fractions of Cu spacer particles. A higher volume fraction of Cu particles resulted in higher thermal conductivity.

Figure 2

X-ray diffraction pattern of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams fabricated using Cu spacer particles by employing the hot press method.

Figure 3

High-resolution transmission electron microscope images of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams fabricated using 10 vol.% of Cu spacer particles. (a) Selected area electron diffraction (SAED) pattern and (b) nanocrystallization zone.

Figure 4

Scanning electron microscope images depicting the surface morphology of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams with porosities of (a) 10%, (b) 20%, (c) 30%, and (d) 40%. These images indicate the open-cell structure of foams and that the pore size was approximately 120 µm.

Figure 5

Stress–strain curve of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams with different porosities. The compressive strength decreased with increasing porosity.

Figure 6

Prediction of (a) Young’s modulus and (b) compressive strength of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams by using the Gibson and Ashby model.

Figure 7

Cell viability of MC3T3-E1 preosteoblasts cultured with the precipitation medium of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams with porosities of 10%, 30%, and 50% fabricated using different volume fractions of Cu spacer particles and immersion for (a) 1-, (b) 3-, and (c) 7-day incubation (N = 5 per group; * p < 0.05, ** p < 0.01, and *** p < 0.005; N.S., not significant).

Figure 8

Cell migration capacity of MC3T3-E1 preosteoblasts cultured with the precipitation medium of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams with porosities of 10%, 30%, and 50% fabricated using different volume fractions of Cu spacer particles. (a) Cell migration at the first scratch and after 8 h of incubation (control, CTL); (b) the distance of the gap decreased due to the migration of MC3T3-E1 preosteoblasts after 8 h of incubation (N = 5 per group; N.S., not significant).

Figure 9

Extracellular matrix calcium and mineral deposition from MC3T3-E1 preosteoblasts cultured with the precipitation medium of Ti₄₂Zr₃₅Ta₃Si₅Co_12.5Sn_2.5 bulk metallic glass foams with porosities of 10%, 30%, and 50% fabricated using different volume fractions of Cu spacer particles and stained by alizarin red S dye. The results of the stained area of each experimental group are normalized to the control group (N = 5 per group; N.S., not significant).