1,721,065 research outputs found
Developing Magnesium Alloys with a Combination of Strength and Ductility Based on Friction Stir-Based Technologies
No full textSome of the key data for the thesis "Developing Magnesium Alloys with a Combination of Strength and Ductility Based on Friction Stir-Based Technologies", including SEM/EDS/EBSD, and TEM data. They are stored in the .oipx format which can be opened by Aztec, .cpr which can be opened by AztecCrystal, and .csv and . tiff as spreadsheets and images.
Part of the data is associated with the following publications:
[1] X. Zhao, X. Zeng, L. Yuan, J. Gandra, Q. Hayat, M. Bai, W.M. Rainforth, D. Guan, A novel approach for producing Mg-3Al-1Zn-0.2 Mn alloy wire with a promising combination of strength and ductility using CoreFlowTM, Scripta Materialia 227 (2023) 115301.
[2] X. Zhao, Y. Xie, J. Gandra, M. Murphy, W.M. Rainforth, D. Guan, A Succinct Method to Recycle WE43 Mg Alloys—From Wasted Chips to Consolidated Billets, TMS Annual Meeting & Exhibition, Springer, (2024), 151-153.
[3] X. Zhao, D. Olden, B. Williams, A. Pariyar, D. Zhang, M. Murphy, P. Reed, P. Allison, B. Jordon, J. Qi, W. M. Rainforth, D. Guan, Grain growth stagnation at 525° C by nanoparticles in a solid-state additively manufactured Mg-4Y-3RE alloy, Journal of Magnesium and Alloys (2024), 4976-4987.
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Direct observation of precipitation along twin boundaries and dissolution in a magnesium alloy annealing at high temperature
Full text linkPrecipitation along twin boundaries and dissolution in a cold-rolled Mg-Y-Nd alloy was directly observed for the first time during annealing at 490 °C. Precipitation occurred concurrently with recrystallization and the combined effect of precipitation and solute segregated to twin boundaries modified the recrystallization behaviour. Precipitates later dissolved into the matrix at the point where full recrystallization was nearly complete. The precipitates and higher solute concentration along original twin boundaries hindered grain growth of newly formed recrystallized grains. Even where twin boundaries had been consumed by recrystallization, the size of recrystallized grains were still controlled by the pre-existing twin boundaries
Effect of cryomilling time on microstructure evolution and hardness of cryomilled AZ31 powders
Full text linkThe synthesis of nanostructured AZ31 powder by cryomilling was studied in this paper. The microstructural evolution during cryomilling, including the changes of particle morphology and internal grain size, was characterized via optical microscopy, SEM, TEM and XRD. Observations during the cryomilling produced four main findings. Firstly, cryomilling can refine the grains of AZ31 particles down to 100 nm after around 1 h milling and the minimum average grain size of about 30 nm was reached when the cryomilling time was extended to 6 h or longer. Secondly, cold welding played a dominant role in the early stage of cryomilling, while fracture took place in the late stage and surpassed cold welding. The former led to a particle size increase while the latter decreased the particle size. The minimum average particle size after 6 h cryomilling was approximately 26 μm. Thirdly, a few particles were agglomerated with other particles and could not be processed by cryomilling due to cold welding. Finally, after cryomilling 6 h and longer times, the hardness reached 162 HV which was much higher than other values reported in AZ31 alloy studies
ω phase strengthened 1.2GPa metastable β titanium alloy with high ductility
Full text linkThis paper provides a novel approach for exploiting ω phase strengthening in a metastable β titanium alloy while retaining high ductility. The addition of 1 wt% Fe into our previously designed Ti-7Mo-3Cr alloy can efficiently control the growth of ω phase following air-cooling, resulting in a ultrahigh yield strength (Rp0.2of 1210 MPa) with large ductility (εf of 0.15). Microstructural analysis of deformed alloys showed that the growth of ω phase in the air-cooled Ti-7Mo-3Cr-1Fe alloy modified the deformation mechanism from {332} twinning and dislocation slip, in the water-quenched alloy, to localized dislocation plasticity in ω-void channels
Effect of grain size and crystallographic structure on the corrosion and tribocorrosion behaviour of a CoCrMo biomedical grade alloy in simulated body fluid
Full text linkCoCrMo alloys are used in hip and knee replacements due to their excellent long-term survival rates. However, high failure rates have recently been observed associated with adverse tissue reactions. CoCrMo alloy surfaces undergo microstructural changes during wear, including the formation of ε-martensite and, occasionally, a nanocrystalline surface layer. It is not clear whether these changes are beneficial or detrimental to the performance of the component. Thus, high-pressure torsion (HPT) was employed to produce different grain sizes and crystallographic structures in a CoCrMo alloy and the corrosion and tribocorrosion behaviour were critically investigated as a function of grain size. The results reveal a degradation of the corrosion resistance for the HTP processed samples. The contributions of mechanical and corrosion material loss in tribocorrosion is also examined
Enhancing ductility and strength of nanostructured Mg alloy by in-situ powder casting during spark plasma sintering
Full text linkDue to internal processing defects, bulk nanostructured Mg alloys have high strength but extremely poor ductility. A novel and facile process was designed and in-situ powder casting was initiated during spark plasma sintering. This process significantly reduced processing induced defects, enhanced inter-particle bonding and introduced significant precipitation without extra ageing treatment, leading to improvement of the compressive strength and ductility. The compressive strain of bulk sample consisting of pure cryomilled powder was 3.6% with an ultimate strength of 500 MPa, while cryomilled powder mixed with eutectic Mg-Zn alloy powder obtained a compressive strain of 6.6% and ultimate strength of 506 MPa. The ductility of the sample with mixed powder was increased by 83% without any sacrifice of strength compared to the sample consisting of only pure cryomilled powder
Insights into tribofilm formation on Ti-6V-4Al in a bioactive environment: Correlation between surface modification and micro-mechanical properties
No full textTi-6Al-4V has been used as a surgical implant material for a long time because of its combination of strength, corrosion resistance and biocompatibility. However, there remains much that is not understood about how the surface reacts with the environment under tribocorrosion conditions. In particular, the conditions under which tribofilms form and their role on friction and wear are not clear. To evaluate the complicated nature of the dynamic surface microstructural changes on the wear track, high resolution transmission electron microscopy (TEM), scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) have been used to characterise the structure and chemical composition of the tribofilm. Detailed analysis of the formation and structure of the tribofilm and the metal surface deformation behaviour were studied as a function of applied potential and the role of proteins in the lubricant. For the first time, graphitic and onion-like carbon structures from wear debris were found in the testing solution. The presence of carbon nanostructures in the tribocorrosion process and the formation of the tribofilm leads to an improved tribocorrosion behaviour of the system, in particular a reduction in wear and friction. A detailed, quantitative, analysis of surface deformation was undertaken, in particular, the geometrically necessary dislocation (GND) density was quantified using precession electron diffraction (PET). A clear correlation between applied potential, tribofilm formation and the surface strain was established. Statement of significance: The formation of tribofilm and microstructure modification of the Ti-6Al-4V surface during tribocorrosion in a physiological environment is not fully understood. In particular, the correlation between microstructural changes and electrochemical conditions is not clear. This study presents a detailed investigation of the structure and chemical composition of tribofilms at the nanoscale during tribocorrosion tests in simulated body fluid and gives a detailed and quantitative description of the evolved surface structure. A clear correlation between applied potential, tribofilm formation and the surface strain was established. Moreover, particular attention is paid to the wear debris particles captured from the lubricating solution, including nanocarbon onion structures. The implications for tribocorrosion of the alloy in its performance as an implant are discussed.</p
A novel approach for producing Mg-3Al-1Zn-0.2Mn alloy wire with a promising combination of strength and ductility using CoreFlow™
Full text linkMg-3Al-1Zn-0.2Mn (wt.%, AZ31B) wires were successfully produced from commercial hot-rolled plates in one step using the CoreFlowTM process, a novel stationary shoulder friction stir extrusion manufacturing. CoreFlowed AZ31B wires exhibited fine grains with a heterogeneous grain size distribution of 6.5 ± 4.2 μm along the transverse direction (TD) compared with the as-received material. A weakened texture was also obtained in CoreFlowed AZ31B, with basal poles aligned parallel to TD shift toward extrusion direction (ED) from wire center to edge. Periodic needle-like regions with a distinctively different orientation from neighbouring regions were observed at the sample edge. The engineering ultimate tensile strength (UTS) and elongation (El) of the CoreFlowed sample was 258 ± 5 MPa and 22.3 ± 0.8%. The El was significantly increased by 58% with equivalent UTS compared to the as-received material. Such a good combination of strength and ductility is attributed to grain refinement with heterogeneity, texture weakening, and homogeneously redistributed second phase particles
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