Ti-based Glassy Alloy Research Articles

Formation and properties of biocompatible Ti-based bulk metallic glasses in the Ti–Cu–Zr–Fe–Sn–Si–Ag system

The Ni-free Ti-based bulk metallic glasses (BMGs) with high glass-forming ability (GFA) can be synthesized in the (Ti, Cu, Zr)92.5Fe2.5Sn2Si1Ag2 alloy system over a wide composition range by copper-mold casting. Especially, the Ti48Cu37Zr7.5Fe2.5Sn2Si1Ag2 glassy alloy can form the BMG rod with a diameter up to 6 mm and showed a high compressive strength of ~ 2.05 GPa, elastic modulus of ~ 100 GPa, and microhardness of ~ 571 Hv. The Ti-based BMGs presented good bio-corrosion resistance in a simulated physiological environment attributed to the formation of Ti-, Zr-, Si-, and Fe-enriched passive films. The biocompatibility of the Ti-based glassy alloys was systematically investigated by both indirect cytotoxicity test and direct cell-culture experiments. The Ti-based BMG extracts had no cytotoxic effects on the proliferation of the cells. The good cell adhesion, proliferation, differentiation, and mineralization of bone-forming MC3T3-E1 pre-osteoblasts on the BMGs were parallel to those on the Ti–6Al–4V alloy. These results manifested that the present Ti-based BMGs are promising candidates as biomaterials.

Mechanical, corrosion, and wear performances of a biocompatible Ti-based glassy alloy

The mechanical, electrochemical, wear, and corrosive-wear behaviors of a TiZrCuPd bulk glassy alloy were investigated. The Ti-based glassy alloy demonstrates a high yield strength of 2.3 GPa, low Young's modulus of 95 GPa, and Vickers microhardness of 7.2 GPa, which are superior to those of the Ti-6Al-4V biomedical alloy. The TiZrCuPd glassy alloy shows a good corrosion resistance in the phosphate buffer saline (PBS) solution, owing to the formation the Ti- and Zr-enriched passivation film on the alloy surface. The TiZrCuPd alloy displays the lowdry-wear rate of 6.1 × 10−8 mm3 mm N−1and wet-wear rate of 8.0 × 10−8 mm3 mm N−1. The triobocorrosionresults illustrate that the TiZrCuPd alloyshows a high pitting corrosion resistance during the wet sliding, which render its good corrosive wear performance. The good combination of mechanical, corrosion, and wear properties of the Ti-based glassy alloy make it promising for biomedical applications.

Porous Ti-based bulk metallic glass with excellent mechanical properties and good biocompatibility

Porous Ni- and Be-free Ti-based (Ti45Zr10Cu31Pd10Sn4) bulk metallic glass (BMG) with a diameter exceeding 15 mm was developed by spark plasma sintering (SPS) the mixture of gas-atomized Ti-based glassy alloy powder and solid salt (NaCl) powder, followed by leaching treatment to eliminate the salt phase. The thermal and structural stability, microstructure, mechanical properties, corrosion behavior, and biocompatibility of the developed porous Ti-based BMG samples were investigated systematically. The developed porous Ti-based BMG alloy exhibited three times higher yield strength than that of the natural bone, simultaneously matched the Young's modulus of natural bone, and demonstrated high corrosion resistance and excellent biocompatibility. These results suggest that porous Ti-based BMGs produced by the SPS process open an advanced alternative for clinical applications under load-bearing conditions such as surgical implants.

Ni- and Cu-free Ti-based metallic glasses with potential biomedical application

In the present work Ti–Fe–Si and Ti–Fe–Si–X (X = Zr, Pd, Ge) glassy alloys are discussed as potential biomedical materials. Depending on composition and experimental conditions these alloys possess glassy, quasicrystalline or crystalline structure. The glassy state and crystallization behavior of the melt spun ribbons were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and the Hank's solution was used as simulated body fluid for corrosion tests. Ternary Ti–Fe–Si alloys near the Ti65Fe30Si5 eutectic point were prone to form quasicrystals if the cooling rate was not high enough to retain amorphous structure. The compositions on the steeper side of the eutectic point could be vitrified. The results indicate that small additions of Zr can have a positive effect on glass formation, while additions of Ge, Pd may have a detrimental effect by promoting crystallization. Ti–Fe–Si and Ti–Fe–Si–Zr alloys exhibited high corrosion properties, superior to that of pure Ti and most of Ti-based glassy alloys reported in the literature. Being free of Ni and Cu this group of alloys may be considered for possible biomedical application.

New Ti-based Ti–Cu–Zr–Fe–Sn–Si–Ag bulk metallic glass for biomedical applications

A novel Ni-free Ti47Cu38Zr7.5Fe2.5Sn2Si1Ag2 (at.%) bulk metallic glass (BMG) with superior glass-forming ability, good mechanical properties and excellent biocompatibility was discovered. The Ti-based BMG with a diameter of 7mm can be prepared by copper mold casting and the supercooled liquid region was 52K. Compressive strength, specific strength, Young’s modulus and microhardness of the Ti-based BMG were about 2.08GPa, 3.2×105Nm/kg, 100GPa and 588Hv, respectively. Electrochemical measurements indicated that the Ti-based glassy alloy possesses higher corrosion resistance than Ti–6Al–4V alloy in a simulated body fluid environment. Attachment, spreading out and proliferation of MC3T3-E1 cells on the Ti-based BMG surface demonstrated the excellent biocompatibility. Mechanisms of the formation and properties for the Ti-based glassy alloy are also discussed. The combination of high glass-forming ability, excellent mechanical properties, high corrosion resistance and good biocompatibility demonstrates the potential of the Ni-free Ti-based BMG for use in biomedical applications.

Ti-based glassy alloys in Ti-Cu-Zr-Sn system

Bulk amorphous formation in Ti-Cu-based multicomponent alloys, free of Ni, Pd and Be elements, were studied using the cluster-plus-glue-atom model. The basic cluster formula was revealed as [Ti9Cu6]Cu3 to explain the best binary glass forming composition Ti50Cu50=Ti9Cu9, where the CN14 rhombi-dodecahedron Ti9Cu6 was the principal cluster in the devitrification phase CuTi. This basic cluster formula was further alloyed with Zr and Sn and a critical glass forming ability was reached at (Ti7.2Zr1.8)(Cu8.72Sn0.28) and (Ti7.2Zr1.8)(Cu8.45Sn0.55) up to 5 mm in diameter by suction casting, which was the largest in Ti-Cu-based and Ni-, Pd- and Be-free alloys.

Correlation of glass-forming ability to thermal properties in Ti-based bulk metallic glasses

Ti45.8Zr6.2Cu45−xNixSn2Si1 (x=0, 2, 4, 5, 7, 9, 11, 13 and 15at.%) and Ti52−yZryCu40.9Ni5.1Sn2 (y=4, 6, 8, 10, 12, 14 and 16at.%) bulk metallic glasses with critical diameters up to 4mm were prepared by copper mold casting. The thermal properties and crystallization behavior of these Ti-based glassy alloys have been investigated in detail. It is shown that the higher the onset temperature of the last crystallization event (Tn), the larger the glass forming ability (GFA). By considering the comprehensive effect of glass transition temperature (Tg), the onset temperature of the first crystallization event (Tx), Tn and liquidus temperature (Tl), we proposed a parameter N=(2Tx−Tg+Tn)/2Tl for the evaluation of GFA. It is found that this criterion is particularly effective for the BMGs which show multistage crystallization events upon heating.

Formation, mechanical properties and corrosion resistance of Ti–Pd base glassy alloys

No biocompatible Ti-based glassy alloys without a harmful element have been reported. We have examined the mechanical and chemical properties of Ti–Pd–Zr–Si glassy alloy in comparison with pure Ti metal and Ti–6Al–4V alloy which have been used so far for biomaterials. The present Ti–Pd base glassy alloys do not contain Al and Ni elements which are considered to be rather toxic. Melt-spun Ti45Zr50−xPdxSi5 glassy alloy ribbons (x=35, 40, 45) exhibited good bend ductility and had higher Vickers’s hardness and lower Young’s modulus as compared to pure titanium and Ti–6Al–4V alloy. In addition, the Ti45Zr50−xPdxSi5 glassy alloys had higher corrosion resistance and were passivated over a wide range and at the lower passive current density of approximately 10−2Am−2 than at of pure titanium and Ti–6Al–4V alloy in 1mass% lactic acid and PBS(−) solutions at 310K.

Thermal Stability and Mechanical Properties of Ti<SUB>47.4</SUB>Cu<SUB>42</SUB>Zr<SUB>5.3</SUB>TM<SUB>5.3</SUB>(TM = Co, Fe) Metallic Glass Sheets Prepared by Twin-Roller Casting Method

Since Ti-based glassy alloys have high strength and high corrosion resistance, it is useful for an application field of substitution material for biomaterials such as living body bone. For the biomaterial use, the glassy alloys are required to substitute the harmful elements for the human body such as Ni. In the present study, we prepared the Ti47.4Cu42Zr5.3TM5.3(TM = Co, Fe) glassy alloy sheets by a twin-roller casting method, and investigated their thermal stability and mechanical properties. The prepared alloy sheets had flat surfaces with highly white luster, and exhibited a distinct glass transition typical to a glassy phase. The super-cooled liquid region ΔTx defined by the difference between the glass transition temperature (Tg) and the onset temperature for crystallization (Tx) is 50 K for the Ni-containing alloy, 36 K for the Co-containing alloy and 32 K for the Fe-containing alloy. All the alloy sheets exhibit good bending ductility and their Vickers hardness is in the range of 590 to 600.

Lightweight Ti-based bulk metallic glasses excluding late transition metals

Lightweight Ti-based bulk amorphous structural metals with more than double the specific strength of conventional titanium alloys have been discovered. Thermal, elastic and mechanical properties of these metallic glasses were studied and are presented. These amorphous alloys exhibit good glass-forming ability, exceptional thermal stability and high strength. The research results have important implications for designing and developing low-density bulk metallic glasses. The technological potential of this class of lightweight Ti-based glassy alloys as structural metals is very promising.

Annealing-Induced Devitrification Behavior of a Ti<SUB>47.4</SUB>Zr<SUB>5.3</SUB>Ni<SUB>5.3</SUB>Cu<SUB>42.0</SUB> Glassy Alloy

We have investigated devitrification behavior, accompanied by glass transition and precipitation of crystallites, as a function of annealing temperature and time for a Ti 47.4 Zr 5.3 Ni 5.3 Cu 42.0 glassy alloy sheet, together with embrittlement behavior using bending fracture strain test. From kinetic analysis in one DSC profile under a constant heating rate, we can easily estimate the devitrification with temperature and time upon annealing. The glassy alloy became brittle during progressive devitrification in accordance with kinetic estimation. In sharp contrast with a Zr 55 Al 10 Ni 5 Cu 30 glassy alloy, all the precipitations of crystallites (Cu 4 Ti 3 , Ti and CuTi) occur above glass transition temperature (Tg). We found that the Ti-based glassy alloy has large structurally and thermally stable area, which does not brittle up to 1.10 x 10 4 s at 650 K and 1.29 x 10 10 s at 600 K, by experiment and kinetic estimation, respectively.

Fabrication and characterization of Coriolis mass flowmeter made from Ti-based glassy tubes

Bulk metallic glasses (BMGs) have potential applications for both structural and functional components owing to their good mechanical properties. With the aim of demonstrating great engineering value of BMGs, we have developed a direct melt-forming technique based on suction casting for the production of glassy alloy tubes. We have examined the fabrication, structure, geometry, properties and sensor performance of the tubes. We have observed that the Coriolis mass flowmeters using the Ti-based glassy alloy sensor tube exhibit excellent measurement sensitivity compared to the conventional flowmeter manufactured using stainless steel (SUS316) tube.

Thermal stability of mechanically alloyed boride/Ti 50Cu 18Ni 22Al 4Sn 6 glassy alloy composites

The Ti 50Cu 18Ni 22Al 4Sn 6 multicomponent alloy was chosen as base alloy due to a complete glass formation under ball milling and a sizable supercooled liquid region, Δ T x = 66 K. The mixtures of prealloyed Ti 50Cu 18Ni 22Al 4Sn 6 fragments with CrB or TiB 2 particles up to 30 vol.% were mechanically milled to fabricate the boride/Ti-based glassy alloy composites. The structural features of the as-milled products were characterized using X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. In the ball-milled composites, the CrB or TiB 2 particles with sizes ranging around 10–200 nm are dispersed in the Ti-based glassy alloy matrix. Similar to the Ti 50Cu 18Ni 22Al 4Sn 6 glassy alloy without any borides, a well-defined glass transition temperature, T g, and a wide supercooled liquid region, Δ T x, are observed also for the boride-containing composites. Furthermore, the glass transition and thermal stability of supercooled liquid for the matrix alloy in the composites are dependent on the fraction of boride addition. In the case of CrB addition, the Δ T x value of glassy phase matrix was reduced due to a strong fraction dependence of the T g than that of the T x, remaining at about 60 K for boride fractions less than 15 vol.%. In contrast, both the T g and T x of the TiB 2-containing composites were raised with increasing TiB 2 fraction up to 30 vol.%, resulting in no significant change for the Δ T x.

New Ti-Based Bulk Glassy Alloys with High Glass-Forming Ability and Superior Mechanical Properties

Ti-based glassy alloy rods with diameters up to 5 mm were prepared for Ti41.5Zr2.5Hf5Cu42.5Ni7.5Si1 in a multi-component system of (Ti, Zr, Hf)-(Cu, Ni)-Si by conventional copper mold casting. The new mutli-component glassy alloy exhibits moderate thermal stability with a supercooled liquid region (ΔTx) above 50 K. The glass transition temperature (Tg), crystallization temperature (Tx), melting temperature (Tx), liquidus temperature (Tl), and the reduced glass transition temperature (Tg/Tl) are 680 K, 730 K, 1143 K, 1199 K and 0.57, respectively. The cast glassy alloy exhibits compressive strength of 2080 MPa, tensile strength of 2040 MPa and Young's modulus of 100 GPa. The reason for the high glass-forming ability (GFA) of the Ti-based multi-component alloy is discussed on the basis of knowledge available for bulk glass formation.