| 1. |
- Ng, B. S., et al.
(author)
-
Characterisation of a duplex TiO2/CaP coating on Ti6Al4V for hard tissue replacement
- 2005
-
In: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 26:10, s. 1087-1095
-
Journal article (peer-reviewed)abstract
- An initial TiO2 coating was applied on Ti6Al4V by electrochemical anodisation in two dissimilar electrolytes. The secondary calcium phosphate (CaP) coating was subsequently applied by immersing the substrates in a simulated body fluid (SBF) with three times concentration (SBF×3), mimicking biomineralisation of biological bone. Electrochemical impedance spectroscopy and potentiodynamic polarisation assessments in SBF revealed that the anodic TiO2 layer is compact, exhibiting up to four-folds improvement in in vitro corrosion resistance over unanodised Ti6Al4V. X-ray photoelectron spectroscopy analysis indicates that the anodic Ti oxide is thicker than air-formed ones with a mixture of TiO2-x compound between the TiO2/Ti interfaces. The morphology of the dense CaP film formed, when observed using scanning electron microscopy, is made up of linked globules 0.1-0.5ÎŒm in diameter without observable delamination. Fourier transform infrared spectrometry with an attenuated total internal reflection analysis revealed that this film is an amorphous/poorly crystallised calcium-deficient-carbonated CaP system. The calculated Ca:P ratios of all samples (1.14-1.28) are lower than stoichiometric hydroxyapatite (1.67). These results show that a duplex coating consisting of (1) a compact TiO2 with enhanced in vitro corrosion resistance and (2) bone-like apatite coating can be applied on Ti6Al4V by anodisation and subsequent immersion in SBF. © 2004 Elsevier Ltd. All rights reserved.
|
|
| 2. |
- Rastegari, H., et al.
(author)
-
Determination of processing maps for the warm working of vanadium microalloyed eutectoid steels
- 2016
-
In: Materials Science and Engineering: A. - : Elsevier. - 0921-5093. ; 658, s. 167-175
-
Journal article (peer-reviewed)abstract
- Microalloying of an eutectoid steel with V may facilitate formation of dispersed nano-scaled VC particles in the microstructure during thermomechanical processing or subsequent heat treatment. In this research, the constitutive flow behavior of vanadium microalloyed eutectoid steel has been investigated in the temperature range 620–770 °C at strain rates in the range 0.01–10 s−1. Microstructural characterization of the deformed specimens was conducted using SEM and EBSD techniques. In this context, various deformation mechanisms occurring during warm deformation have been characterized and delineated through construction of a processing map by establishing a power dissipation map and an instability map for the steel and superimposing them. The results show that the pearlitic microstructure exhibits several deformation mechanisms within these warm working conditions. Dynamic spheroidization of cementite lamella takes place in the range 660–720 °C and 0.01–0.1 s−1 with a power dissipation efficiency of 27–33%, characterizing a safe window of processing this steel. The presence of vanadium carbides at grain boundaries strengthened the pearlitic microstructure and retarded the occurrence of some deformation defects during low temperature, high speed deformation in the range 620–720 °C and 1–10 s−1.
|
|
| 3. |
- Danno, A., et al.
(author)
-
Effect of cold severe deformation by multi directional forging on elastic modulus of multi functional Ti+25mol% (Ta,Nb,V)+(Zr,Hr,O) alloy
- 2010
-
In: Materials & Design. - : Elsevier BV. - 0261-3069. ; 31:SUPPL. 1, s. S61-S65
-
Journal article (peer-reviewed)abstract
- A new and unique beta-titanium alloy (Ti. +. 25. mol% (Ta,Nb,V). +. (Zr,Hr,O) has interesting properties such as low elastic modulus, high strength and high elastic deformability as well as Invar and Elinvar properties. These properties have been successfully realized for the round wire or rods by cold working process but not enough for the sheet made by the cold rolling.To improve the mechanical properties of the alloy sheet, the effect of cold severe deformation on the elastic modulus and microstructure of the alloy sheet was experimentally investigated. The samples were processed using the multi directional forging (MDF) and cold plain rolling.The elastic modulus of the alloy sheet which was cold rolled after MDF was lower than that of cold rolled sheet without MDF. The severe cold plastic deformation by MDF was also effective for obtaining isotropic elastic modulus and very fine grain size (∌1ÎŒm) of sheet after plain rolling. The prototype sheet with low elastic modulus (60-65. GPa), high strength (1100. MPa) and high ductility (total elongation more than 10%) was successfully made in the laboratory test by combining MDF and plain rolling at room temperature. © 2009 Elsevier Ltd.
|
|
| 4. |
- Ekbom, L. B., et al.
(author)
-
Liquid phase sintering of tungsten composites under microgravity : Influence of liquid/particle surface energy
- 1991
-
In: Advances in Space Research. - 0273-1177 .- 1879-1948. ; 11:7, s. 331-335
-
Journal article (peer-reviewed)abstract
- Tungsten-nickel-iron heavy metals are fabricated from powders by liquid phase sintering. A study of the sintering mechanism of heavy metals with a low amount of tungsten particles can, depending on sedimentation, only be done under microgravity. At two earlier Texus flights, No 10 & 19, the growth rate and agglomeration of tungsten particles under microgravity were compared to that under gravity and sedimentation. During the first minute sintering period the particles in the agglomerates were separated and the particle distribution became even. The particle growth rate under microgravity, initially high, is slowing down. At further studies under gravity the influence of surface energy between the liquid phase and the tungsten particles have been investigated. Additions of sulphur and cobolt were used to decrease the surface energy and the use of nickel without iron to increase the energy. At a high surface energy the growth rate increases due to increased driving force. Preliminary results from the Texus 26 flight (April 90) are included. © 1991.
|
|
| 5. |
- El-Mahallawy, N., et al.
(author)
-
On the reaction between aluminum, K2TiF6 and KBF4
- 1999
-
In: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 292:1-2, s. 221-229
-
Journal article (peer-reviewed)abstract
- The reaction between molten Al and KBF4 and K2TiF6 was analyzed. Additions of the two salts separately, consecutively and simultaneously were made at 800 and 1000 °C. The phases formed were identified and their morphology investigated. When adding K2TiF6 emulsification of the salt occurs. Residual salt containing K, Ti, Al and O was found in addition to slag containing K, Al and O. In an emulsified region, a new globular morphology of Al3Ti-type was found. No evidence of emulsification of KBF4 was found. This implies that the two salts react individually with Al. A new morphology of AlB2, in the form of thin plates, formed presumably at the salt/aluminum interface, was also found.
|
|
| 6. |
|
|
| 7. |
- Awe, Samuel A., et al.
(author)
-
Development of new Al-Cu-Si alloys for high temperature performance
- 2017
-
In: Advanced Materials Letters. - : VBRI Press. - 0976-3961 .- 0976-397X. ; 8:6, s. 695-701
-
Journal article (peer-reviewed)abstract
- In a quest to develop new light metal alloys that can perform excellently at elevated-temperatures (from 300°C to 400°C), a ternary eutectic Al-Cu-Si alloy was exploited to gain a deeper understanding of the alloy system and its suitability for high temperature applications. The alloys studied, with chemical composition of Al-27%Cu-5%Si (by weight percent) with Ni addition in the range of 0 to 1.5%wt, were cast in a rapid solidification casting technique. The solidification characteristics of the alloy was studied using the Thermo-Calc software. Microstructures were characterized in a scanning electron microscope coupled with energy dispersive spectrometry (SEM-EDS). Finally, the elevated-temperatures tensile properties of the alloys were investigated. Comparing the microstructures and mechanical properties of these Al-Cu-Si(-Ni) alloys with conventional Al-Si alloy A319, the refined microstructure with dispersed Ni intermetallic particles formed in the as-cast Al-Cu-Si(-Ni) alloys deliver improved elevated temperature properties. In particular, the yield strength and ultimate tensile strength of the new alloy with 1.5% Ni at 400?C were observed to be 220% and 309% higher, respectively, than for conventional A319 alloy.
|
|
| 8. |
|
|
| 9. |
- Bi, G., et al.
(author)
-
Feasibility study on the Laser Aided Additive Manufacturing of die inserts for liquid forging
- 2010
-
In: Materials & Design. - : Elsevier BV. - 0261-3069. ; 31:SUPPL. 1, s. S112-S116
-
Journal article (peer-reviewed)abstract
- This paper reports the Laser Aided Additive Manufacturing of nickel-base alloy Nimonic 80A for the purpose of direct building of die inserts for liquid forging. Low porosity level of 0.01-0.04% with reasonable deposition rate was achieved. The micro-hardness showed very good homogeneity. Directionally solidified cellular micro-structure with an average size of 5Όm was observed. Very fine MC-type carbides were detected at the grain boundaries, which function as the strengthening phase of the alloy. © 2009 Elsevier Ltd.
|
|
| 10. |
- Ceschini, Lorella, et al.
(author)
-
High temperature tensile behaviour of the A354 aluminum alloy
- 2014
-
In: Materials Science Forum. ; 794-796, s. 443-448
-
Journal article (peer-reviewed)abstract
- The high temperature tensile behaviour of the A354 casting aluminum alloy was investigated also evaluating the influence of secondary dendrite arm spacing (SDAS). Cast specimens were produced through a gradient solidification equipment, obtaining two different classes of SDAS, namely 20-25 µm (fine microstructure) and 40-50 µm (coarse microstructure). After hot isostatic pressing and T6 heat treatment, the samples underwent mechanical characterization both at room and high temperature (200 °C). Results of tensile tests and hardness measurements were related to the microstructural features and fractographic characterization, in order to investigate the effect of microstructure and high temperature exposure on the mechanical behaviour of the alloy.
|
|
