Essay On Slip In Nb

Thermo-mechanically affected zone (TMAZ): In this region, the material has been plastically deformed by the friction stir welding tool, and the heat from the process will also have exerted some influence on the material. In the case of aluminium, it is possible to get significant plastic strain without recrystallization in this region, and there is generally a distinct boundary between the recrystallized zone and the deformed zones of the TMAZ. In the earlier classification, these two sub-zones were treated as distinct microstructural regions. However, subsequent work on other materials has shown that aluminium behaves in a different manner to most other materials, in that it can be extensively deformed at high temperature without recrystallization. In other materials, the distinct recrystallized region (the nugget) is absent, and the whole of the TMAZ appears to be recrystallized. This is certainly true of materials which have no thermally induced phase transformation which will in itself induce recrystallization without strain, for example pure titanium, b titanium alloys, austenitic stainless steels and copper. In materials such as ferritic steels and a-b titanium alloys (e.g.Ti-6Al-4V), understanding the microstructure is made more difficult by the thermally induced phase transformation, and this can also make the HAZ/TMAZ boundary difficult to identify

Aluminium (AL) alloy 6061 is one of the most extensively used of the 6000 series aluminium alloys. Among the various useful aluminium alloys, aluminium alloy 6061 is typically characterized by properties such as fluidity, cast ability, corrosion resistance and high strength-weight ratio. Aluminium-based alloy MMCs has received increasing attention in recent decades as engineering applications. This alloy has been commonly used as a base metal for MMCs reinforced with a variety of fibres, particles and whiskers. Tungsten carbide (WC) is approximately two times stiffer than steel, with a Young's modulus of approximately 550GPa, and is much denser than steel or titanium.

Fig. Tribological coupling: Pin CoCr–Disc Peek 450G at 20 N in air, dry condition and water lubrication. (a) Friction and (b) wear.

The development of materials used in harsh conditions is a very active field of research. This is mainly due to the broad range of industrial applications and of large interest in the development of equipment for oil and gas industry. [1] In that respect, different stainless steels have been proposed in the last decades and they are nowadays used in industry. Though they are not as recognized as carbon steels, there is a steady growth that indicates the necessity to understand the atomistic details of its performance, its potential crystallographic phases and the changes of the elastic and corrosive properties for different alloying agents. The atomistic and microstructure knowledge is a decisive factor in the design of a specific alloy. This will provide us with the local understanding of the alloy and how the properties can be modified by the inclusion of other atoms.

A modified cutoff function for Tersoff potential has been proposed in this paper, to estimate the realistic mechanical behavior of single sheet of graphene. Success of any molecular dynamics based simulation entirely depends on the empirical potential employed for estimating the interatomic interaction forces. Cutoff distance in Tersoff potential that was earlier chosen arbitrarily has now been optimized. Simulations were performed at different set of temperatures and strain rate to validate the modified Tersoff potential with the existing experimental results. In detail comparison has also been made with respect to mechanical behavior of graphene estimated with the help of modified Tersoff potential and other potentials AIREBO, 2nd generation REBO and optimized Tersoff.

This report is to highlight the methods, results and theory relevant during an engineering experiment called “cold rolling of metals". The purpose of this report is to show how readings obtained from the set-out experiment, can be evaluated to determine the behavior of 3 selected materials; Brass, Copper and Aluminium through the process of cold rolling. The form of the materials are in small strips which are processed via cold-rolling method 4 times from their original state to evaluate the effects incurred on hardness values, width, length and thicknesses. Hardness values/vickers numbers are determined for each material using a Vickers hardness tester and the measurements of width, length & thickness taken using a vernier

nature of the M and A elements, MAX phases tend to be relatively soft and readily machinable (due to weak

Dispersion strengthening usually design in nuclear power plants , hypersonic aircraft , and space vehicles are continually seeking materials that have high strength at elevated temperature . These requirements have been met in part by the precipitation-strengthened “supperalloys” that are suitable for application up to around 1800°F . The refractory metals , tungsten , molybdenum , columbium , and tantalum , may sometimes be used when the service temperature exceeds the useful temperature of the super alloys . However , the refractory metals are expensive , difficult to fabricate , and have poor resistance to oxidation . There is a limit to which one can extend the service temperature by precipitation strengthening . In

Structural defects which are inevitable during the production, chemical and heat treatment processes can affect the mechanical properties of graphene and also defects can be deliberately introduced in graphene by ion beam irradiation to get required properties for specific applications. So, understanding the effect of defects on mechanical properties and failure behaviours of a graphene sheet is important for its applications. In this work, the effects of linear and angular orientation of different types of Stone-Thrower-Wales (STW-1 and STW-2) defects on the mechanical properties and failure behaviour of graphene membrane have been investigated in the frame of molecular dynamics. This work discussing about tuneable mechanical properties by amending the linear orientation of STW-1 and STW-2 defects at different angles in zigzag direction and armchair direction respectively. The results obtained from the present work may provide the insights in tailoring the mechanical properties by preparing defects in graphene, and give a full picture for the applications of graphene with defects in flexible electronics and nanodevices.

Conceptually, CLS is quite a simple phenomenon; solute elements, which in this case consist of alloying elements (e.g. Manganese and Carbon) or impurities (e.g. Sulphur and Phosphorous) are more soluble in liquid phases than solid phases of similar temperatures; this is known as solute rejection. The difference in solubility causes the solute atoms to be pushed away from solidification fronts within the steel. For CC steel, solidification begins on the outer surface of the structure being cast, leading to solidification fronts that move from the outside surface of the steel to the inside. The outside-to-inside movement of the

Graphene is a hexagonal two-dimensional (2D) monolayer of honeycomb lattice packed carbon structure that was discovered and successfully isolated from bulk graphite just a few years ago [1]. It is a promising candidate in a number of mechanical, thermal and electrical applications [2-6], owing to its outstanding physical properties [2]. In addition to enormous nano-technological applications, graphene also attracts prodigious attention as strengthening element in composites [7-10]. Characterization of the mechanical properties of graphene is essential both from a technological perspective for its reliable applications and from a fundamental interest to understanding its deformation physics [11-13]. In material science, fracture toughness is a property that describes the ability of a material containing a crack to resist fracture, and is one of the most important mechanical properties of any material [14-15]. The useful strength of large area graphene with engineering relevance is usually determined by its fracture toughness, rather than the intrinsic strength

The mechanical properties of graphene sheet can be tailored with the help of topological defects. In this research article, the effects of Stone-Thrower-Wales (STW) defects on the mechanical properties of graphene sheet was investigated with the help of molecular dynamics (MD) based simulations. Authors has made an attempt to analyse the stress field developed in and around the vicinity of defect due to bond reorientation and further systematic evaluation has been carried out to study the effect of these stress fields against the applied axial compressive load. The results obtained with the pristine graphene were made to compare with the available open literature and the results were reported to be in good agreement with theoretical and experimental data. It was predicted that graphene with STW defect cannot able to bear compressive strength in zigzag direction, whereas on the other hand it was predicted that graphene sheet containing STW defect can bear higher compressive load in armchair direction, which shows an anisotropic response of STW defects in graphene. From the obtained results it can be observed that orientation of STW defects and the loading direction plays an important role to alter the strength of

Structural defects which are inevitable during the production, chemical and heat treatment processes can affect the mechanical properties of graphene and also defects can be deliberately introduced in graphene by ion beam irradiation to get required properties for specific applications. So, understanding the effect of defects on mechanical properties and failure behaviours of a graphene sheet is important for its applications. In this work, the effects of linear and angular orientation of different types of Stone-Thrower-Wales (STW-1 and STW-2) defects on the mechanical properties and failure behaviour of graphene membrane have been investigated in the frame of molecular dynamics. This work discussing about tuneable mechanical properties by amending the linear orientation of STW-1 and STW-2 defects at different angles in zigzag direction and armchair direction respectively. The results obtained from the present work may provide the insights in tailoring the mechanical properties by preparing defects in graphene, and give a full picture for the applications of graphene with defects in flexible electronics and nanodevices.

Solidification is process through which crystalline materials, such as metals and alloys, transform from non-crystallized state into crystallized state. This process is a basic technique used in alloy casting, growth of single-phase semiconductors, welding and etc. We need to understand what’s happening during solidification and how it affect the structure of final materials, which directly determines the properties of products. Besides, a proper set of solidification parameters also helps to improve energy efficiency.

Also, refined layers with nano-grains (grain size of approximately 40 nm) were formed in the cryogenically burnished surface, in which an average hardness increase of 9.5%, 17.5% and 24.8% within the 200 m depth are achieved in comparison with the hardness values obtained from dry burnishing, at the corresponding burnishing speeds of 25, 50 and 100 m/min. Refined surface layers with ultra-fine grains or nano-grains could be generated during the burnishing process due to imposed severe plastic deformation and the associated dynamic recrystallization (DRX). These harder layers with compressive residual stresses induced by the burnishing process also provide added benefits by enhancing wear/corrosion resistance and increasing the fatigue life of the components.