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1.
The effect of Sn substitution for Si on the glass forming ability (GFA) and crystallization behavior has been studied in Ni59Zr20Ti16Si5 − xSnx (x=0, 3, 5) alloys. A bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy with diameter up to 3 mm can be fabricated by injection casting. Partial substitution of Si by Sn in Ni59Zr20Ti6Si5 − xSnx alloys improves the glass forming ability. The improved GFA of the Ni59Zr20Ti16Si2Sn3 alloy is can be explained based on the lowering of liquidus temperature. The crystallization sequence becomes completely different with addition of Sn. The amorphous Ni59Zr20Ti16Si5 alloy crystallizes via precipitation of only a cubic NiTi phase in the first crystallization step, whereas the amorphous Ni59Zr20Ti16Si2Sn3 alloy crystallizes via simultaneous precipitation of orthorhombic Ni10(Zr,Ti)7 and cubic NiTi phases. Addition of Sn in the Ni59Zr20Ti16Si5 alloy suppresses the formation of the primary cubic NiTi phase. The bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy exhibits high compressive fracture strength of about 2.7 GPa with a plastic strain of about 2%. 相似文献
2.
We have produced a series of bulk metallic glasses of composition (HfxZr1−x)52.5Cu17.9Ni14.6Al10Ti5 (with x=0-1) by an arc melting/suction casting method. The density of these alloys increases by nearly 67% with increasing Hf content from 6.65 g/cm3 (x=0) to 11.09 g/cm3 (x=1). Over the same composition range the glass-forming ability decreases, as demonstrated by the size of the largest amorphous ingots that can be cast without crystallization. Although both the glass transition temperature and the melting temperature increase linearly with increasing Hf content, the reduced glass transition temperature (Tg/Tm) decreases, from 0.64 (x=0) to 0.62 (x=1), which suggests that the `confusion principle' correlating increased glass-forming ability with increased number of components, does not apply in this case due to the chemical similarity between Zr and Hf. A different crystallization behavior is observed for Zr-based and Hf-based glasses. The final crystalline phases are CuZr2 and Zr2Ni for Zr-based alloys, and Al16Hf6Ni7 and CuHf2 for Hf-based alloys. 相似文献
3.
Glass-forming ability (GFA) of Ti–Ni–Sn ternary alloys was investigated. Applying recent models based on atomic size ratio and efficient packing, the composition favoring the glass formation is predicted. Our experiments indicate that the optimized glass-forming composition is located at Ti56Ni38Sn6, with the critical thickness of complete glass formation approaching 100 μm for the melt-spun ribbons. The Ti56Ni38Sn6 metallic glass exhibits a sizable supercooled liquid region (ΔTx) of about 35 K and a reduced glass transition temperature (Trg) of 0.52. We demonstrate that the glass formation of the Ti56Ni38Sn6 alloy correlates with the (L → TiNi + Ti3Sn) pseudo binary eutectic reaction in Ti–Ni–Sn ternary system, which has an invariant temperature and composition at ~1370 K and ~Ti58Ni34Sn8, respectively. With respect to Sn-free Ti–Ni binary alloys, the GFA is enhanced for the Ti–Ni–Sn ternary alloys, but the improvement is limited possibly due to changes in the crystalline phases competing with glass formation. 相似文献
4.
The thermal stability, kinetics of crystallization, and glass forming ability of a Ti48Ni32Cu8Si8Sn4 bulk amorphous alloy have been studied by differential scanning calorimetry using both isothermal and non-isothermal experiments. The activation energy, frequency factor, and reaction rate for the crystallization cascade were determined via the Kissinger method. X-ray diffractometry and transmission electron microscopy studies revealed that crystallization starts with the primary precipitation of Ti(Ni,Cu), followed by the nucleation of Cu3Ti from the amorphous precursor. The kinetics of nucleation of the primary crystalline phase was also investigated using the Johnson–Mehl-Avrami method and the Avrami exponent, n, was determined. This new alloy possesses a significantly larger supercooled liquid region than any other non beryllium- or non rare earth – containing titanium-based bulk metallic glass to date. 相似文献
5.
Potentiodynamic polarization studies were carried out on virgin specimens of Zr-based bulk amorphous alloys Zr46.75Ti8.25Cu7.5Ni10Be27.5 and Zr65Cu17.5Ni10Al7.5, and conventional-type binary amorphous alloys Zr67Ni33 and Ti60Ni40 in solutions of 0.2 M, 0.5 M and 1.0 M HNO3 at room temperature. The values of the corrosion current density (Icorr) for the bulk amorphous alloy Zr46.75Ti8.25Cu7.5Ni10Be27.5 were found to be comparable with those of Zr65Cu17.5Ni10Al7.5 in 0.2 M and 0.5 M HNO3, but the value of Icorr for the former was almost three times more than that of the latter in 1.0 M HNO3. In the case of conventional binary amorphous alloys, Ti60Ni40 showed lower value of Icorr as compared to Zr67Ni33 in 0.5 M and 1.0 M HNO3 and a comparable value of Icorr in 0.2 M HNO3. In general, the binary Ti60Ni40 displayed the best corrosion resistance among all the alloys in all the cases and the corrosion current density (Icorr) for all the alloys was found to increase with the increasing concentration of nitric acid. It is noticed that the bulk amorphous alloys do not possess superior corrosion resistance as compared to conventional binary amorphous alloys in aqueous HNO3 solutions. The observed differences in their corrosion behavior are attributed to different alloy constituents and composition of the alloys investigated. 相似文献
6.
The influence of outphase Cu50Ti50 amorphous alloy addition on microstructural evolution of Zr66.7Ni33.3 amorphous alloy has been investigated using a mechanical alloying method. It has been found that the milling induced microstructural evolution is related to the change of peak positions of the first maximum on X-ray diffraction patterns of the as-obtained amorphous alloys. With increasing milling time, the 3 wt.% Cu50Ti50 addition can give rise to the cyclic amorphization transformation of the as-milled alloy. The mechanical stability of the mixing amorphous phase can be greatly enhanced with increasing Cu50Ti50 addition up to 10 wt.%. Moreover, the addition of outphase Cu50Ti50 amorphous alloy not only increases the onset crystallization temperature of Zr66.7Ni33.3 amorphous alloy but also alters its crystallization mode. The effect of outphase amorphous addition on the mechanical stability of the Zr66.7Ni33.3 amorphous phase has been discussed based upon the bond order theory. 相似文献
7.
The crystallization of amorphous Zr54Cu46 alloy was investigated by using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) techniques. The experimental results show that an endothermic peak in DSC traces for amorphous Zr54Cu46 alloy exists at about 1006 K, indicating following eutectoid reaction occurs, namely, Cu10Zr7+CuZr2↔CuZr in amorphous Zr54Cu46 alloy during heating. With increasing the heating rate, the glass transition temperature Tg and onset crystallization temperature Tx of amorphous Zr54Cu46 alloy increase in parallel, and the supercooled liquid region ΔTx (=Tx−Tg) holds almost constant with an average value of 44 K. Both XRD and TEM results prove that Cu10Zr7 and CuZr2 are main crystallization products for amorphous Zr54Cu46 alloy under continuous heating conditions. No CuZr phase is identified because of its small precipitation amount. Finally, the crystallization processes of amorphous Zr54Cu46 alloy were summarized. 相似文献
8.
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 10−2 Am−2 than at of pure titanium and Ti-6Al-4V alloy in 1 mass% lactic acid and PBS(−) solutions at 310 K. 相似文献
9.
《Journal of Non》2007,353(32-40):3338-3341
A series of glass forming alloys (Ti33Zr33Hf33)100−x−y(Ni50Cu50)xAly (x = 20–70 at.% and y = 0–30 at.%) have been developed by equiatomic substitution of similar elements. Of these alloys (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 was chosen in this study to investigate the structural relaxation and glass transition behavior. The as-quenched (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy was fully amorphous and had a wide supercooled liquid region ΔT = Tx(503 °C) − Tg(433 °C) = 70 °C, where Tg and Tx are the glass transition and crystallization temperatures, respectively. Low temperature pre-heat treatments of the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy for 10 min at 310 °C, 370 °C and 390 °C caused structural relaxation accompanied by the formation of very fine scale lattice ordering. After these heat treatments, the glass transition became hard to observe in the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy. Increasing the pre-heat treatment temperatures and holding times caused the glass transition to become more clearly detectable with increasing endothermic heat release. 相似文献
10.
《Journal of Non》2001,279(2-3):154-160
The effect of Ag substitution for Cu on the glass forming ability was studied in Mg65Cu25−xAgxY10 (x=0,5,10,15,20,25) alloys by using thermal analysis and X-ray diffractometry (XRD). With increasing x from 0–25, the glass transition temperature, Tg, of melt spun Mg65Cu25−x AgxY10 alloys increases slightly from 426 to 436 K, and the crystallization temperature, Tx, decreases from 494 to 459 K, resulting in a decrease in the supercooled liquid region. However, a partial substitution of Cu by Ag in Mg65Cu25Y10 promotes the glass formation. The maximum diameter for amorphous phase formation by injection casting increases from 4 mm in Mg65Cu25Y10 to 6 mm in Mg65Cu15Ag10Y10 alloy. Both amorphous Mg65Cu15Ag10Y10 alloys prepared by melt spinning and injection casting showed similar crystallization process during continuous heating in differential scanning calorimetry (DSC). The relationship between the critical diameter for the formation of an amorphous phase in injection casting and the parameters reflecting glass-forming ability was examined. 相似文献
11.
As-cast (Ti40Zr25Ni8Cu9Be18)100−xNbx (0 ? x ? 5) (Ф3) glassy forming alloys were investigated in order to clarify the role of Nb on the formation of icosahedral quasicrystalline phase (I-phase) in Ti-rich Ti-Zr-Ni-Cu-Be glassy system. It is found that an I-phase is formed in Ti-Zr-Ni-Cu-Be glassy alloy by addition of Nb element; however, the nucleation rate of I-phase increases, whereas the grain growth rate decreases with increasing Nb content. Moreover, with increasing Nb content, the thermal stability against crystallization increases, while the temperature range of stability of the I-phase decreases. 相似文献
12.
Refractory bulk metallic glasses and bulk metallic glass composites are formed in quaternary Ni-Nb-Ta-Sn alloy system. Alloys of composition Ni60(Nb100−xTax)34Sn6 (x = 20, 40, 60, 80) alloys were prepared by injection-casting the molten alloys into copper molds. Glassy alloys are formed in the thickness of half mm strips. With thicker strips (e.g., 1 mm), Nb2O5 and Ni3Sn phases and the amorphous phase form an in situ composite. Glass transition temperatures, crystallization temperatures, and ΔTx, defined as Tx1 − Tg (Tx1: first crystallization temperature, Tg: glass transition temperature) of the alloys increase dramatically with increasing Ta contents. These refractory bulk amorphous alloys exhibit high Young’s modulus (155-170 GPa), shear modulus (56-63 GPa), and estimated yield strength (3-3.6 GPa). 相似文献
13.
《Journal of Non》2007,353(24-25):2346-2349
Metallic glasses are kinetically metastable materials. These amorphous materials can be transformed into a crystalline state by both isothermal and isochronal methods. The study of this transformation, and hence the thermal stability of metallic glasses, are important from an application view-point. In the present work, the non-isothermal crystallization kinetics of two titanium-based amorphous alloys namely, Cu50Ti50 and Ti50Ni30Cu20, are reported. The activation energies for crystallization, Ec for both the systems have been evaluated using different non-isothermal methods viz. derived through Kissinger, Augis and Bennet and Ozawa. The values of Ec obtained using these methods are consistent for both the metallic glasses and it is found that Ec for the ternary metallic glass is considerably higher than the binary metallic glass. The increase in the activation energy on the substitution of Ni in the Cu–Ti metallic glass suggests the increase in the thermal stability. 相似文献
14.
Thermal embrittlement of amorphous Fe78?xNixSi10B12 and Co78Si10B12 alloys has been studied. The majority of Fe-based amorphous alloys became brittle after annealing to temperatures significantly lower than their crystallization temperatures, whereas the non-Fe-based amorphous alloys remained ductile after annealing up to their crystallization temperatures. The present results emphasize on the key difference between the embrittlement behavior of Fe-based and non-Fe-based amorphous alloys. We point out a possible correlation between different phenomena like Invar effect, compositional inhomogenity, and residual stress playing a critical role in the thermal embrittlement of Fe-based amorphous alloys. 相似文献
15.
《Journal of Non》2007,353(8-10):845-847
Amorphous Ni59Zr20Ti16Sn5 alloys were fabricated by melt spinning and by mechanical alloying (MA) techniques. Additionally the melt spun ribbon was powdered by ball milling. Differential scanning calorimetry (DSC) measurements revealed two or three-steps crystallization of the amorphous alloys. MA powders exhibited the lowest crystallization temperature of the first DSC peak, the melt spun ribbon – the highest one. On the other side, the lowest value of activation energy of crystallization was calculated for ball milled ribbon. Further studies are needed to clarify the differences in thermal stability and crystallization behavior of the alloys. 相似文献
16.
The isochronal crystallization kinetics of the Ti40Zr25Ni8Cu9Be18 metallic glass has been investigated by differential scanning calorimetry (DSC). Results indicate that the two crystallization events of this metallic glass cannot be well-described by the classic Johnson-Mehl-Avrami (JMA) kinetic equation. The kinetic equation considering the impingement effect has been found more applicable for describing the isochronal crystallization kinetics of this amorphous alloy. Accurate values of kinetic parameters were determined by fitting the theoretical DSC data to experimental curves. The kinetic parameters change in different crystallization stages and show strong heating rate dependence. Reasons of the deviation from the JMA kinetics for the isochronal crystallization of Ti40Zr25Ni8Cu9Be18 metallic glass were discussed. 相似文献
17.
《Journal of Non》2007,353(8-10):1008-1010
The aim of this work has been the systematic study of the influence of partial substitution of Fe by Ni in the NixFe73.5−xSi13.5B9Nb3Cu1 alloy within the range 0 ⩽ x ⩽ 10% atom (x = 0, 2, 4, 6, 8, 10) on electrochemical behavior, corrosion rate and the structural changes in amorphous and nanocrystalline alloys. The amorphous nature of the alloys was confirmed by X-ray diffraction and the chemical compositions were determined by ICP. The glass transition and kinetic crystallization of amorphous alloys were studied by DSC. The technique of XPS was used for evaluating the chemical states of elements present in native oxide films. The electrochemical behavior of amorphous and nanocrystalline alloys have been investigated in 0.5 M KOH using cyclic voltammetry. The experimental results show that the formation of different nanocrystalline phases is not excessively transformed by the addition of small amount of nickel and the electrochemical behavior is improved as nickel content increased. 相似文献
18.
The crystallization behavior and microstructure development of the Zr61Al7.5Cu17.5Ni10Si4 alloy during annealing were investigated by isothermal differential scanning calorimetry, X-ray diffractometry and transmission electron microscopy. During isothermal annealing of the Zr61Al7.5Cu17.5Ni10Si4 alloy at 703 K, Zr2Cu crystals with an average size of about 5 nm were first observed during the early stages (30% crystallization) of crystallization by TEM. The Zr2Cu crystal size increased with annealing time and attained an average size of 20 nm corresponding to the stage of 80% crystallization. In addition, the change in particle size with increasing annealing time exhibited a linear relationship between grain growth time and the cube of the particle size for the Zr2Cu type crystalline phase. This indicates that the crystal growth of the Zr61Al7.5Cu17.5Ni10Si4 alloy belongs to a thermal activated process of the Arrhenius type. The activation energy for the grain growth of Zr2Cu is 155 ± 20 kJ/mol in the Zr61Al7.5Cu17.5Ni10Si4 amorphous alloy. The lower activation energy for grain growth in compared to that for crystallization in Zr65Cu35 440 kJ/mol crystal corresponds to the rearrangement of smaller atoms in the metallic glass, Al or Si (compare to Zr). 相似文献
19.
In the present paper, the effect of carbon on the microstructural evolution of Zr66.7−xNi33.3Cx (x = 0, 1, 3) alloys during mechanical alloying has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that these three alloys undergo similar amorphization and crystallization processes, and the final milling product is a metastable fcc-Zr66.7−xNi33.3Cx phase. The carbon addition can shorten the milling time for the complete amorphization reaction and enhance the stability of the formed amorphous alloy, which can suppress the mechanically induced amorphous-crystalline phase transformation with further increasing milling time. 相似文献
20.
《Journal of Non》2007,353(32-40):3425-3428
The formation of bulk metallic glasses (BMG) in the Cu-rich Cu–Zr–Ti ternary system is studied by using the ‘e/a-variant line criterion’. Three such lines, (Cu9Zr4)1−xTix, (Cu61.8Zr38.2)1−xTix and (Cu56Zr44)1−xTix, are defined in the Cu–Zr–Ti system by linking three binary compositions Cu9Zr4, Cu61.8Zr38.2 and Cu56Zr44 to the third element Ti. The binary compositions Cu9Zr4, Cu61.8Zr38.2 and Cu56Zr44 correspond to specific Cu–Zr binary clusters. BMGs are obtained by copper mould suction casting method with Ti contents of 7.5–15 at.%, 7.5–12.5 at.% and 5–12 at.%, respectively along the (Cu9Zr4)1−x Tix, (Cu61.8Zr38.2)1−xTix and (Cu56Zr44)1−xTix lines. The BMGs on each composition line manifest decreased thermal stabilities and glass forming abilities (GFAs) with increasing Ti contents. The maximum GFA appears at Cu64Zr28.5Ti7.5, with characteristic thermal parameters of Tg = 736 K, Tx = 769 K, Tg/Tl = 0.627 and γ = 0.403, which are all superior to those reported for the known Cu60Zr30Ti10 BMG. 相似文献