The mechanical properties and deformation behaviour of a selective laser melted (SLMed) Ti6Al4V alloy were investigated at the micro-scale via in situ micro-pillar compression. The microstructure of ...the alloy consists of acicular martensite (α′) compared to the bi-modal α/β microstructure of a mill-annealed alloy of similar composition. This microstructure, together with loading direction with respect to build direction, affects the mechanical properties and gives rise to anisotropy. Irrespective of build orientation, both the yield and the ultimate compressive strength of the alloy is about 1.8 times more than that of the mill-annealed alloy. The rise of anisotropy was related to the presence of prior β grain orientation with that of the loading direction and is discussed in relation to predominant fracture mechanisms. TEM investigation on the deformed micropillars showed the existence of a vast network of dislocations, stacking faults and compression twinning{101‾2}; which was identified as a load accommodation mechanism during deformation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study investigates the deformation of Al-based metal matric composites (MMCs) under in-situ micro-pillar compression. Different sizes of SiC nanoparticles, namely 55 nm and 700 nm, were used as ...reinforcing medium in the MMCs. Such in-situ compression shows real time deformation of materials and helps to correlate materials’ response with corresponding stress-strain curves. It was shown that, MMCs exhibit higher yield strength compared to monolithic Al, thanks to effective load bearing among reinforcement and matrix. Whereas monolithic Al experience substantial work hardening, MMCs experience blocking of dislocations and slip/shear bands by the presence of reinforcing nanoparticle. These gives rise superior strength on MMCs compared to monolithic Al6061 alloy, which is about two times higher.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Electrodeposited multilayered gradient coatings were successfully deposited with distinct and uniform layer thickness and subjected to physical and mechanical characterization.•Flow strength of ...multilayered Co-Sn gradient coating is higher than that of sole Co or Sn coating.•After compression, coating structure exhibit four distinctive layers instead of starting seven, due to elemental inter-mixing of intermediate thin layers as a stress accommodating mechanism.
Compositionally modulated multilayer (CMM) Co-Sn coating were successfully deposited with the help of electrodeposition on copper substrate. The coating microstructure was homogeneous, nanostructured in nature with smooth and distinct interfaces as confirmed by SEM and TEM investigation. In this study, micro-mechanical properties of such CMM Co-Sn coatings has been investigated by means of micro-pillar compression. Micro-mechanical properties of electrodeposited monolithic sole Co and sole Sn coatings was also investigated for comparison purpose. CMM Co-Sn coating shows high flow strength of about 330 MPa, which is about 1.2 and 5 times higher than that of sole Co and sole Sn coating, respectively. Such enhanced mechanical properties are the result of intermixing of several thin Co-Sn layers to form a single broad layer to accommodate deformation of material and to minimize system’s energy as evident by detail transmission electron microscopy investigation on deformed micro-pillars.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Hematopoietic stem cell transplant (HCT) recipients have a substantial risk of developing secondary solid cancers, particularly beyond 5 years after HCT and without reaching a plateau overtime. A ...working group was established through the Center for International Blood and Marrow Transplant Research and the European Group for Blood and Marrow Transplantation with the goal to facilitate implementation of cancer screening appropriate to HCT recipients. The working group reviewed guidelines and methods for cancer screening applicable to the general population and reviewed the incidence and risk factors for secondary cancers after HCT. A consensus approach was used to establish recommendations for individual secondary cancers. The most common sites include oral cavity, skin, breast and thyroid. Risks of cancers are increased after HCT compared with the general population in skin, thyroid, oral cavity, esophagus, liver, nervous system, bone and connective tissues. Myeloablative TBI, young age at HCT, chronic GVHD and prolonged immunosuppressive treatment beyond 24 months were well-documented risk factors for many types of secondary cancers. All HCT recipients should be advised of the risks of secondary cancers annually and encouraged to undergo recommended screening based on their predisposition. Here we propose guidelines to help clinicians in providing screening and preventive care for secondary cancers among HCT recipients.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Fatigue cracks don’t follow machining traces.•The course and nature of cracks depend on the reinforcement size.•Fractured surfaces are very similar regardless of particles size and machining ...conditions.•The larger particles reduce the fatigue life at all interacting parameters.
This study investigates fracture and fatigue performance of metal matric composites (MMCs) without any reinforcement and, 0.7 and 13 µm particle (10 vol%) reinforced which were machined at different feeds and speeds. Fractured surface as well as fatigue generated cracks were investigated in details. The effect of interactions among input machining parameters with their variations on fatigue life has also been analysed. It was found that fatigue cracks don’t follow machining traces. Moreover, the cracks are almost straight and sharp when reinforcing particles are smaller but change the course, and surface along the crake is highly damaged when the reinforced particles are bigger. The appearance of fractured surfaces of the samples are very similar regardless of particles size and machining conditions. Though compressive residual stress is generated on the machined MMC surfaces, fatigue life of MMCs are much shorter than that of corresponding matrix material due to the fracture and detachment of reinforcing particles from matrix. Fatigue life has an initial decreasing trend with the rise of feed-rate and then it increases significantly with further increase of feed-rate in the absence of particles machine at low speed. However, fatigue life remains almost constant with the increase of feed-rate for larger particle reinforced MMC machined at high speed. With the increase of speed, opposite trends on fatigue life were noticed for MMCs and matrix material when machined at low and high feeds, respectively. The larger reinforced particles reduces the fatigue life of machined specimens at every interacting combinations of parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
Uniaxial random field disorder induces a spontaneous transverse magnetization in the XY model. Adding a rotating driving field, we find a critical point attached to the number of driving ...cycles needed to complete a limit cycle, the first discovery of this phenomenon in a magnetic system. Near the critical drive, time crystal behavior emerges, in which the period of the limit cycles becomes an integer
n
> 1 multiple of the driving period. The period
n
can be engineered via specific disorder patterns. Because
n
generically increases with system size, the resulting period multiplication cascade is reminiscent of that occurring in amorphous solids subject to oscillatory shear near the onset of plastic deformation, and of the period bifurcation cascade near the onset of chaos in nonlinear systems, suggesting it is part of a larger class of phenomena in transitions of dynamical systems. Applications include magnets, electron nematics, and quantum gases.
Non-conventional machining process for instance, wire electrical discharge machining (WEDM) of titanium alloys is gaining attention due to non-contact nature of this process. To deepen the ...understanding in this area, this study investigates surface generation, kerf width, discharge gap, material removal rate and wire degradation during WEDM of Ti6Al4V alloy. Pulse on time (4–10 μs), flushing pressure (7–18 MPa) and wire tension (800–1700 gf) were varied and resulting influences on output parameters were analysed. It was found that, machined surfaces consist of multi-layered recast layer with the presence of cracks, holes as well as traces of materials from electrode wire. The composition and roughness of the machined surface varies slightly with respect to machining condition without following any trend. In addition, deformation and morphology of deformed wire electrode after the WEDM process was also reported in this study.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
9.
Burr formation and its treatments—a review Jin, Song Yong; Pramanik, A.; Basak, A. K. ...
International journal of advanced manufacturing technology,
03/2020, Volume:
107, Issue:
5-6
Journal Article
Peer reviewed
Burrs, being one of the most undesired obstructions generated during machining, affects work piece quality negatively in many aspects. Although deburring removes burrs, this extra process is time ...consuming, costly and might affect dimensional accuracy. This study investigates mechanisms, effects and variations on burr formation in most common machining processes such as drilling, milling, turning and grinding based on the information available in literature. The problems related to burrs as well as ways and methods to remove burr and control or minimize burr formation has critically discussed. Burrs can be minimised by selecting proper tool geometry, tool materials, coolant, machining parameters, work piece material, process planning and tool path design. As there is no method that can eliminate burr formation, thus deburring is essential to eliminate burrs after machining. Manual tools, abrasive blasting, abrasive flow, magnetic abrasive finishing, centrifugal barrel finishing, thermal melting and electrochemical effect are most commonly used for deburring depending on material, size and precision of parts.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Frequency is an important parameter in power system monitoring, control, and protection. A least mean square (LMS) algorithm in complex form is presented in this paper to estimate power system ...frequency where the formulated structure is very simple. The three-phase voltages are converted to a complex form for processing by the proposed algorithm. To enhance the convergence characteristic of the complex form of the LMS algorithm, a variable adaptation step-size is incorporated. The performance of the new algorithm is studied through simulations at different situations of the power system.
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