#microstructures

kalmness-kid:

My new MATE shirt, for those that aren’t MatEs the microstructure on the shirt is Pearlite, which is often mistaked as a phase when it is actually 2 phases in a llamelar structure(ferrite+cementite).

Sorry about squinting it was really bright today.

Al 75, Cu 25 (wt%), hypoeutectic alloy

Processing: Sand cast

[…]

Sample preparation: Etched in sodium hydroxide solution

Technique: Reflected light microscopy

Length bar: 40 μm

Further information: The micrograph shows primary Al dendrite arms (white). The dendrite trunk has been intersected at an angle by the plane of polishing to give the observed morphology. Between the dendrites is the Al - CuAl₂ eutectic. Initially dendrites would have formed from the liquid, the regions between the dendrite arms known as the mushy zone transforming to a eutectic solid (L to Al + CuAl₂). These two phases form cooperatively as neighbouring lamellae with the lateral diffusion of material across the growing interface. The relative amounts of the two phases (Al and CuAl₂ ) within the eutectic are determined by applying the Lever Rule at the eutectic temperature.

Contributor: Prof T W Clyne

Organisation: Department of Materials Science and Metallurgy, University of Cambridge

Source. 

journal-of-science:

The Effects of Hot Isostatic Pressing of Platinum Alloy Castings on Mechanical Properties and Microstructures http://www.technology.matthey.com/article/59/3/207-217/

Scientists discover new field affecting metals solidification

A fundamental discovery that alters our current understanding of how metals solidify and form crystalline patterns may help lead to better control of casting and welding processes. It also explains how snowflakes and many mineral patterns form naturally.

Reexamining data from his 20-year-old NASA experiment involving the repeated freezing and melting of high-purity materials in microgravity, Martin Glicksman, research professor in materials science and the Allen Henry Chair at Florida Institute of Technology, working with Kumar Ankit at the School of Matter, Transport and Energy at Arizona State University, discovered the way nature guides formation of complex patterns in materials that crystallize.

Glicksman discovered an energy field affecting all crystallizing substances, which he labeled the bias field that he believes is nature’s way of guiding cellular and branching dendritic microstructures that form during solidification of most metals and alloys.

“In the last phases of melting, needle-like crystals suddenly changed to spheres, and so for the first time ever, as we watched stationary particles melting in microgravity and observed their rather remarkable shape change,” Glicksman said.

Read more.

cenchempics:

SCARY STORIES TO TELL IN THE LAB

This image may look torn from the pages of a horror novel, but it actually depicts a possible new manufacturing method for electronic devices that work with living tissues. A team at Georgia Tech is studying the use of protein biofilms to direct the orderly formation of semiconducting polymer chains. Greater order in the chains could mean better and more predictable electronic properties for devices such as biocompatible sensors or electrodes. The researchers mixed poly(3-hexylthiophene) with a fungal protein called cerato-ulmin in the solvent 1,2,4-trichlorobenzene. As the proteins assembled into biofilms, the polymer collected in stable microstructures (dark areas above). These structures over time formed spindly branches, which slowly budded to release polymer-containing capsules. The team is now working on understanding and controlling the details of this process.

The resemblance to Stephen Gammell’s illustrations from the book series “Scary Stories to Tell in the Dark” is a happy accident.

Credit:Chem. Mater. 2015, DOI: 10.1021/acs.chemmater.5b04192

miguelparedes:

The study of metallurgy and materials require of the knowledge of microstructures. Here is a microstructure of a non-chemical-attacked metal (steel1010). We can see absolutely nothing but little dots. This remarks the importance of chemical attacks to unveil the microstructure of metals.

Engineers Develop Automated Process for Discovering Optimal Structure for Metamaterials

For decades, materials scientists have taken inspiration from the natural world. They’ll identify a biological material that has some desirable trait — such as the toughness of bones or conch shells — and reverse-engineer it. Then, once they’ve determined the material’s “microstructure,” they’ll try to approximate it in human-made materials.

Researchers at MIT’s Computer Science and Artificial Intelligence Laboratory have developed a new system that puts the design of microstructures on a much more secure empirical footing. With their system, designers numerically specify the properties they want their materials to have, and the system generates a microstructure that matches the specification.

The researchers have reported their results in Science Advances. In their paper, they describe using the system to produce microstructures with optimal trade-offs between three different mechanical properties. But according to associate professor of electrical engineering and computer science Wojciech Matusik, whose group developed the new system, the researchers’ approach could be adapted to any combination of properties.

“We did it for relatively simple mechanical properties, but you can apply it to more complex mechanical properties, or you could apply it to combinations of thermal, mechanical, optical, and electromagnetic properties,” Matusik says. “Basically, this is a completely automated process for discovering optimal structure families for metamaterials.”

Read more.

study-tea-mse:

2/5/18

Microstructures homework and progress on a report for my material design class about Brinell, Vickers macrohardness, and Rockwell B. There is never a dull moment. 

kalle1277:

Forging blank (Titanium, grade 1): taken pictures with polarized light || on the left side: oxygenated edge area (needles visible) || on the right side: regular microstructure in the core area

kalle1277:

Austenitic microstructure with small amount of Delta-ferrite (on the left side: etched conventionally || on the right side: etched with Beraha)

Researchers gain a better understanding of the transformation of steel

Heating iron can alter its structure and is one of the methods for making various types of steel with different properties. That process is similar to the formation of frost flowers: one iron crystal structure transforms into another at a nucleus point, and the process expands further from that point. This type of nucleation in materials has the largest impact on their final properties, but is still the least understood in the field of metallurgy. For example, we still know little about how and where exactly this nucleation starts. Researchers at TU Delft have now shed new light on this subject in their publication ‘Preferential Nucleation during Polymorphic Transformations’ in Scientific Reports(Nature) of Wednesday 3 August.

The researchers demonstrated this nucleation process live by heating an iron sample to 1,000 degrees in a specially produced furnace at the European Synchrotron Radiation Facility in Grenoble, and monitoring the transformation process using X-rays. In this way, they were able to identify the places and their properties that were the most likely starting points for the nucleation process of the transition from ferrite to austenite.

Read more.