Zinc thiourea sulphate (ZTS) structure
The micrograph shows zinc thiourea sulphate (ZTS) structure in dielectric ceramic
The micrograph shows dendrite structure of a copper-phosphorus alloy, 400 microns
Al 67, Cu 33 (wt%), eutectic alloy
This SEM image shows the lamellar eutectic very clearly. The interlamellar spacing is about one micron. There are several imperfections in the lamellar structure, which have arisen from irregularities and disturbances during growth.
Microwave dielectric ceramics system 1-1-4
The micrograph shows structure of a BaO-Nd2O3-4TiO2 ceramics, 400 microns
Fe, C 0.2 (wt%), explosively deformed - mechanical twins
This sample was explosively deformed so that there was insufficient time for dislocation motion to occur. Hence, mechanical twins are produced despite the b.c.c. structure of mild steel.
Virtual yeast cell
This rich learning object is used to introduce yeast cytology to students taking Module D24BS3 Brewery Yeast Management as part of the MSc in Brewing Science. The virtual cell permits the students to understand structure and function of yeast organelles.
Conservation and biodiversity
Dr. Richard Field research interests lie in conservation, biodiversity and the forces that structure ecological communities. In this podcast, Dr Field from the School of Geography compares and contrasts his experiences as a researcher in national parks in Honduras and Indonesia, and the different types of ecological communities he has studied, and goes on to introduce the emerging field of conservation bio-geography.
Enhancing Physics Knowledge for Teaching – Atoms and Light
In this session we shall look at how light interacts with atoms. This will enable us to determine the internal structure of atoms and also the quantum behaviour of light.
TALAT Lecture 2710: Static Design Example
Example of structure design of the industrial building developed with the Mathcad software.
FOAMCARP closed cell aluminium foam
Additions such as SiC are made to molten aluminium or aluminium alloy to modify the melt viscosity and make it suitable for foaming. Calcium carbonate is then added to the melt which is solidified to form a precursor which can be foamed in a controlled manner by a subsequent heat treatment. The resulting foam has a fine and relatively uniform cell structure.
Cu 55, Zn 45 (wt%) brass, as cast, dendritic
A cast alloy of high zinc brass, consisting of β dendrites. The α precipitates out of solution at the crystal boundaries, forming a structure of β dendrites surrounded by α. This is known as a Widmanstätten structure because a geometrical pattern of α forms on certain crystallographic orientations of the β lattice.
High magnification SEM image of open cell polyurethane foam
If a gas is injected into a liquid it forms a cellular foam structure. When a thermoset prepolymer of low viscosity is foamed, the polymer can drain from the cell walls (driven by surface tension) before it sets at the cell edges, leaving an open-celled foam. The cell edges have three concave sides, and some remnants of collapsed cell walls can be seen at the cell edges.
Fe, Ni 30, C 0.3 (wt%), quenched - martensite plates
This sample was quenched to -80 °C to give a metastable martensitic microstructure. The martensite plates show a lenticular morphology as the material attempts to shear as it transforms but is unable to open up voids at the grain boundaries. The plates form in a similar way to mechanical twins but the shear processes lead to changes in crystal structure as well as crystallographic orientation.
This sample shows the typical structure of silal, irons with high Si content (5.5-7.9 wt%). It is a grey cast iron alloyed with 4-6wt% Si to provide good oxidation resistance. The high Si content forms a dense, adherent iron silicate surface film, which is resistant to oxygen penetration. The flake graphite iron Silal was one of the first heat resisting cast irons developed. Spheroidal graphite Si irons have higher strength and improved ductility. The structure shows cored dendrites of ferrite w
Thin section of ZnO varistor
The micrograph shows structure of ZnO, containing small amounts of oxides such as Sb2O3 and Bi2O3. Thin section was produced using liquid phase sintering: gives rise to a structure consisting of conductive ZnO grains with the additional oxides being preferentially located at grain boundaries. A varistor is used to short-circuit transient high voltage spikes in electronic devices. Incorporated into circuits, in parallel with the device to be protected. Acts as an insulator below a certain breakdo
FORMGRIP closed cell aluminium foam
Additions such as SiC are made to molten aluminium or aluminium alloy to modify the melt viscosity and make it suitable for foaming. 1 to 3 wt% of pre-oxidised titanium hydride is then added to the melt which is solidified to form a precursor which can be foamed in a controlled manner by a subsequent heat treatment. The resulting foam has a relatively fine and uniform cell structure.
Cu 70, Ni 30 (wt%), cored dendrites
This alloy is typical of many copper based alloy systems. The dendrite structure shows coring (variation in solute concentration). The light areas are rich in nickel and the darker areas are low in nickel. Chill casting extracts heat quickly enough to prevent significant solid state diffusion, resulting in cored dendrites. The centres of the dendrites that cool near the liquidus temperature, are nickel rich compared to the outer layers that solidify at progressively lower temperatures. Because t
Deeply etched dendrites (cobalt samarium copper)
Using this alloy composition, a relatively low volume fraction of pro-eutectic dendrites are formed. The eutectic material between these dendrites can be etched away to reveal the three-dimensional structure of dendrites. The dendrite tips are a volume of revolution, and anisotropy develops behind them with the secondary dendrite arms.See R. Glardon, W. Kurz, "Solidification path and phase diagram of directionally solidified Co-Sm-Cu alloys", J. Cryst. Growth, 51 (1981) 283-291.
Zn, cold rolled - mechanical twins
This sample was cold rolled. Zinc has a hexagonal structure so it contains only two independent slip systems. However, for slip to occur, five slip systems are required so zinc does not undergo general plasticity. Instead it forms mechanical twins as an alternative to dislocation motion to accommodate the deformation.
Anisotropic quartz rotated between crossed polarisers
Anisotropic quartz rotated through 180° between crossed polarisers. The intensity of light transmitted through the analyser varies as a function of the angle of rotation of the quartz sample in the plane of the filters. At certain orientations, no light is transmitted. These "extinction positions" are found at 90° intervals. From TLP: Atomic Scale Structure of Materials, http://www.msm.cam.ac.uk/doitpoms/tlplib/atomic-scale-structure/index.php