Microstructure

In this study, Cu-Al-B4C metal matrix composite (MMC) material was produced by using hot pressing at powder metallurgy (PM) process. Powder samples were prepared in proportion as 5%, 10% and 20% B4C was added in to Cu-%5 Al powder mixture. Prepared powder samples subject to hot pressing at 600 oC, 4 minutes under argon inert gas atmosphere, 30 MPa/cm2 pressure. Pressed specimens were investigated hardness and microstructure. At the result of the experiments, it's fastened down; B4C affected the hardness and microstructure of the materials, which added at the different rates in matrix.

Streszczenie W pracy przedstawiono sposób otrzymywania i wyniki pomiarów wáaĞciwoĞci fizycznych ceramiki (Pb1-xLax)(Zr1-yTiy) O3, gdzie x= 0, 03 lub 0, 06, y= 0, 9 (PLZT) oraz (Pb1-xLax)[(Zr1-yTiy) 1-zSnz] O3, gdzie x= 0, 04, y= 0, 9, z= 0, 02, 0, 04, 0, 06, 0, 08 (PLZTS). Materiaáy te naleĪą do roztworów staáych tlenowooktaedrycznych o strukturze typu perowskitu. Badane materiaáy zostaáy wykonane przy uĪyciu klasycznej technologii ceramicznej z wykorzystaniem tlenków. Przedstawione zostaáy wyniki badaĔ ...

The exoskeleton of the lobster Homarus americanus is a multiphase biological composite material which consists of an organic matrix (crystalline α-chitin fibers and various types of non-crystalline proteins) and minerals (mainly calcite). In this study we discuss experimental data about the mesoscopic structure and the crystallographic texture (orientation distribution) of the α-chitin–protein fiber network in this material. The synchrotron measurements reveal very strong crystallographic textures of the α-chitin. According to these data, a large fraction of the α-chitin lattice cells is arranged with their longest axis parallel to the normal of the surface of the exoskeleton. Additionally, a smaller fraction of the α-chitin cells is oriented with their longest axis perpendicular to the cuticle surface. These structural investigations reveal the pronounced role of crystallographic orientation distributions in mineralized biological composite materials which may be of relevance for an improved understanding of biological and bio-inspired nano-composites.

AISI 316 austenitic stainless steels have been plasma nitrided using a dc glow discharge unit in order to investigate the influence of gas composition on microstructure and corrosion behavior of treated samples. Corrosion properties of untreated and plasma nitrided 316 steels ...

The oxygenation process of the top seeded melt-grown (TSMG) single-grain YBa2Cu3O7/Y2BaCuO5 (123/211) bulk superconductors was studied by microstructure observations. It is shown that the c-cracks in these bulks are formed in the oxygenated orthorhombic layer along the a/b-macrocracks. The lattice contraction of the 123 phase in a/b-plane induces tensile stresses in the oxygenated layer, which cannot be relaxed by twin boundary motion. The critical spacing of the c-macrocracks, λcr=14 μm, at oxygenation temperature 380 °C, estimated using Thoules’s model, is in a good agreement with the c-macrocrack spacing measures on standard TSMG 123/211 single-grain samples.

One way of computing the macroscopic behavior of a material sample with complex microstructure is to construct a finite element model based on a micrograph of a representative slice of the material. The quality of the results produced with such a model obviously depends on the quality of the constructed mesh. In this article, we describe a set of routines that modify and improve the quality of a 2D mesh. Most of the routines are guided by an effective element ‘‘energy” functional, which takes into account the shape quality of the elements and the homogeneity of the elements as determined from an underlying segmented image. The interfaces and boundaries in the image arise naturally from the segmentation process. From these routines, we construct a close-to-automatic mesh generator that requires only a few inputs, such as the linear sizes of the largest and smallest features in the micrograph.

In the present work, we report the inicrostructural and mechanical properties of
failed coupling wit/i an airlock in a flour ini!!. The coupling n’hich was made 01
alumniniuni alloy is used to transmit torque froimi the electric motor to an airlock used
on (1 flour miiill production line. The tracture that occurred at the root of the teeth of
tim e coupling wa in i ‘estigated using i ‘arious tests and ana lys is. The tests includes.
miiacro examination, micro—structural examination, composition analysis, hardness
and tensile test were employed for this ¡11H stigation. From the tests carried out, it was
observed from tue macro examination that the coupling undergoes a brittle failure.
Howe ver, composition analysis revealed a relative/v high weight composition of
aluminium (87.5 wt. %) suggesting that the coupling was made of alumnimiiumn based
alloy. The significant presence of Cu and Zn at 2.77 ii’t. % and 1.03 wi. % respectively
indicates that the alloying elements were mainly of copper and zinc. The tensile test
result revealed that the immaterial lias an ultimate tensile strength of 1 78 N/mm2 ii’h ic/i
is comparatively lower than most aluminium alloys. This might be as a result of the
high Si comilpositiomi of 7.24 wt. % obseri’edtroiii the ciiemiiüil comnpositiomial analvsis.
The hardness result showed the Brine/I hardness of the fractured saliij)leS as 76.53
BHN. The mnicrostructure of time coupling at three different sections gave threeMicrostructural and Mechanical Properties of Failed Coupling with An Airlock In A Flour Mill
http://www.iaeme.com/ IJMET/index.asp 796 editor@iaeme.com
different micrographs, further proving uneven distribution of the aluminium alloy
element. Thus, the presence of Si at relatively high percentage, often intended to
increase the strength, wear resistance and weldability may be detrimental to the
coupling ductility and tensile strength and may have contributed to the early fracture
of the coupling.

This article studies the properties of a wide range of friction-stir-welded joints with dissimilar aluminum alloys or thicknesses. Two aluminum alloys, namely, 2024-T3 and 7075-T6, are selected for the study and are welded in ten different combinations of alloys and thicknesses. The ...

The importance of breakfast cereal flakes (BCF) in Western diets deserves an understanding of changes in their mechanical properties and microstructure that occur during soaking in a liquid (that is, milk or water) prior to consumption. The maximum rupture force (RF) of 2 types of breakfast flaked products (BFP)--corn flakes (CF) and quinoa flakes (QF)--were measured directly while immersed in milk with 2% of fat content (milk 2%) or distilled water for different periods of time between 5 and 300 s. Under similar soaking conditions, QF presented higher RF values than CF. Soaked flakes were freeze-dried and their cross section and surface examined by scanning electron microscopy. Three consecutive periods (fast, gradual, and slow reduction of RF) were associated with changes in the microstructure of flakes. These changes were more pronounced in distilled water than in milk 2%, probably because the fat and other solids in milk become deposited on the flakes' surface hindering liqu...