Simultaneous high strength and large ductility are always desirable for metallic materials. However, while the strength of metals and alloys can be easily increased by five to 15 times through simple plastic deformation or grain refinement down to the nano-scale, the gain in strength is usually accompanied by a drastic loss of uniform ductility. Ductility depends strongly on the work hardening ability, which becomes weak in materials with high strength, especially in a single-phase material.
Publishing online in PNAS, the research group of Prof. WU Xiaolei at the Chinese Academy of Sciences, in collaboration with Prof. En Ma at Johns Hopkins University, U.S., have demonstrated a strategy for exploiting a dynamically reinforced multilevel heterogeneous grain structure (HGS). They demonstrated the behavior of such an HGS using the face-centered-cubic CrCoNi medium-entropy alloy (MEA) as a model system.
Back stress hardening is usually not obvious in single-phase homogeneous grains. To overcome this, the scientists purposely created an unusually heterogeneous grain structure. They took advantage of the low stacking fault energy of the MEA, which facilitates the generation of twinned nano-grains and stacking faults during tensile straining, dynamically reinforcing the heterogeneity on the fly.
Purdue University researchers have developed a superstrong material that may change some manufacturing processes for the aerospace and automobile industries.
The Purdue team, led by Xinghang Zhang, a professor in Purdue’s School of Materials Engineering, created high-strength aluminum alloy coatings. According to Zhang, there is an increasing demand for such materials because of their advantages for automakers and aerospace industries.
“We have created a very durable and lightweight aluminum alloy that is just as strong as, and possibly stronger than, stainless steel,” Zhang said. “Our aluminum alloy is lightweight and provides flexibility that stainless steel does not in many applications.”
Another member of the Purdue team, Yifan Zhang, a graduate student in materials engineering, said the aluminum alloy they created could be used for making wear- and corrosion-resistant automobile parts such as engines and coatings for optical lenses for specialized telescopes in the aerospace industry.
In my endless quest for the perfectly machined paper weight I came up with this. From one solid piece of T6 6061 billet aluminum. These are not seperate cubes put inside one another,it was all machined as a whole,the inner cubes do not come out.
Among the most popular aluminum alloys, 6061 aluminum is an alloy in the 6000 series of aluminum alloys: those heat treatable alloys where the principle alloying elements are magnesium and silicon. Because it is so popular, 6061 aluminum is also one of the least expensive of the aluminum alloys.
Highly resistant to corrosion, this alloy can be tempered a variety of different ways to achieve the desirable properties. Different tempers can alter the workability, weldability, and strength. T6 is one of the most common tempers (solution heat treated and artificially aged), but other tempers include O (annealed), T1 (cooled from elevated temperature shaping process and naturally aged), and T4 (solution heat-treated and naturally aged).
6061 aluminum is composed of over 95% aluminum with small or trace amounts of silicon, iron, copper, manganese, magnesium, chromium, zinc, and titanium added in. Magnesium is the largest alloying element, at up to 1.2% maximum, followed by silicon at 0.80% maximum. It is very often extruded but is also suitable for hot forging.
While not as high strength as some of the other aluminum alloys, 6061 is still highly versatile and used in a wide variety of applications: railway car components; boat or aircraft structures; other structural components such as bridges; pipes; wheels; cans; and SCUBA tanks.
A team of researchers affiliated with several institutions in Germany and Poland has demonstrated driven space-time crystals at room temperature. In their paper published in the journal Physical Review Letters, the group describes applying theories surrounding space-time crystals to magnons and how doing so allowed them to exploit electron spin in a way that could prove useful in information technology applications.
Crystals are defined by repeating pattern structures. Other research (by Frank Wilczek in 2012) has suggested that space-time crystals are defined in similar ways with structures that repeat in both time and space. More recent work has led to describing roadmaps for their creation in a lab setting. In this new effort, the researchers have used magnons (quasiparticles that are collective excitations of the spin structure of electrons in a crystal) to realize driven space-time crystals in a room temperature environment. The hope is that such structures, with their new state of matter, can be used to store information with far more energy efficiency than technologies in use now.
To create their space-time crystals, the researchers placed a length of nickel-iron alloy in a radio frequency field. Doing so resulted in the creation of excited magnons, which pushed them to assume a dynamic pattern—the researchers described them as similar to balls on a pool table, though in this case, all the balls returned to their initial positions after passing out of the radio frequency field.
One of the most common methods of improving the corrosion resistance of steel is coating it with other metals such as aluminum (Al). But the use of Al in marine applications is limited owing to its tendency to react with chloride ions in sea water, leading to corrosion. The addition of other elements, such as magnesium (Mg) and silicon (Si), to form an alloyed coating is a promising way around this problem. But Mg cannot be easily deposited as a coating using the conventional method of dipping the steel into a hot bath of metal salts.
In a recent study published in Corrosion Science, scientists have developed a new protocol for Al-Mg-Si coating of steel. “When I served in the navy, I was constantly looking at rusting machinery. Since then, I have become fully engaged in research on how to produce better anti-corrosive steels,” says Professor Myeong-Hoon Lee of the Korea National Maritime and Ocean University, who guided the study. This study was made available online on September 9, 2021 and was published in Volume 192 of the journal in November 2021.
EPFL engineers have developed a low-temperature annealing method that maintains the structure of gold and silver when the two metals are combined in an alloy. Their discovery will prove useful in the manufacture of contact lenses, holographic optical elements and other optical components, since the new alloys reflect the full spectral range.
Gold, silver, copper and aluminum are widely used in the manufacture of optical components because of their reflective properties. Gold, for instance, reflects red light, while silver reflects blue light. These metals are also of interest to scientists, who study them at the nanoscale, since nanostructures have a completely different optical response than bulk materials. At this scale, light interacts differently than it would with the same metal in a larger quantity, such as in a gold bar. Engineers at the Nanophotonics and Metrology Laboratory (NAM), part of EPFL’s School of Engineering (STI), set themselves a challenge: to develop a material that reflects every color in the spectrum.
Just in time for the icy grip of winter: A team of researchers led by scientists from the U.S. Department of Energy Lawrence Berkeley National Laboratory (Berkeley Lab) has identified several mechanisms that make a new, cold-loving material one of the toughest metallic alloys ever. Nanoscale…
What happens when gold and silver just don’t cut it anymore? You turn to metallic alloys, which are what Army researchers are using to develop new designer materials with a broad range of capabilities for our Soldiers.
This is exactly what scientists Dr. David Baker and Dr. Joshua McClure from the U.S. Army Research Laboratory are doing to lighten the load and enhance the power of Soldier devices used on the battlefield.
Their research, conducted in collaboration with Prof. Marina Leite and Dr. Chen Gong at the University of Maryland and Prof. Alexandre Rocha at the Universidade Estadual Paulista in Brazil, was recently featured on the cover of the Sept. 4 issue of Advanced Optical Materials.
The research paper, “Band Structure Engineering by Alloying for Photonics,” focuses on control of the optical and plasmonic properties of gold and silver alloys by changing alloy chemical composition.
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.
A new heating method for certain metals could lead to improved earthquake-resistant construction materials.
Tohoku University researchers and colleagues have found an economical way to improve the properties of some ’shape memory’ metals, known for their ability to return to their original shape after being deformed. The method could make way for the mass production of these improved metals for a variety of applications, including earthquake-resistant construction materials.
Most metals are made of a large number of crystals but, in some cases, their properties improve when they are formed of a single crystal. However, single-crystal metals are expensive to produce.
Researchers have developed a cheaper production method that takes advantage of a phenomenon known as ‘abnormal grain growth.’ By using this method, a metal’s multiple 'grains’, or crystals, grow irregularly, some at the expense of others, when it is exposed to heat.
The team’s technique involves several cycles of heating and cooling that results in a single-crystal metal bar 70 centimetres in length and 15 millimetres in diameter. This is very large compared to the sizes of current shape memory alloy bars, making it suitable for building and civil engineering applications, says Toshihiro Omori, the lead researcher in the study.
An alloy of copper and zinc that has been known about since ancient times, brass is stronger and more durable than its base components, though not as strong as steel. It has stuck around for so long because it’s easy to work with, though the malleability depends upon the zinc content, and is used in decorations and applications where low friction is required.
Brass is a substitutional alloy, typically composed of around 67% copper and 33% zinc. Alloys with less zinc are occasionally called red brass while alloys with more zinc (above 45%) are known as white brasses (and are not commonly used industrially). The table below shows some of the common classifications.
Other elements commonly added to brass include tin, iron, arsenic, antimony, aluminum and potentially small amounts of manganese, silicon, and phosphorus. Lead is also a common additive, though it is becoming less common thanks to growing concerns about its toxicity.
Aside from the properties mentioned above there are many more reasons why brass is a desirable metal. The high copper content makes brass anti-microbial, making it ideal for use in commonly touched items. Brass is also fairly corrosion resistant, allowing it to be used in plumbing. Instruments made of brass are also extremely common thanks to the alloys workability and durability.
The Periodic Table may not sound like a list of ingredients but, for a group of materials scientists, it’s the starting point for designing the perfect chemical make-up of tomorrow’s jet engines.
Inside a jet engine is one of the most extreme environments known to engineering.
In less than a second, a ton of air is sucked into the engine, squeezed to a fraction of its normal volume and then passed across hundreds of blades rotating at speeds of up to 10,000 rpm; reaching the combustor, the air is mixed with kerosene and ignited; the resulting gases are about a third as hot as the sun’s surface and hurtle at speeds of almost 1,500 km per hour towards a wall of turbines, where each blade generates power equivalent to the thrust of a Formula One racing car.
‘There are relatively few metals and alloys that are both ductile and strong enough at room temperature to withstand the cold drawn into wire. Platinum, silver, iron, aluminium, gold, copper, and alloys such as brass and bronze all have suitable properties.’
1. The earliest known example of metal being formed into wire comes from ancient Egypt almost 5,000 years ago.
2. The current method of wire drawing involves pulling ductile metal through a small hole in a die at room temperature.
3. Traditionally, wires used for electrical applications are usually coated in insulating polymers such as polyethylene or PVC.
4. Wires comprise a number of smaller strands, the smallest number being seven – one in the centre with six surrounding it. Some flexible wires can contain up to 100 individual strands.
5. Wires used in nanotechnology are 1D materials, made from metallic (Ni, Pt, Au), semiconducting (Si, InP, GaN) or insulating (SiO2, TiO2) materials.
For more on the history of wire, read Anna Ploszaski’s Material of the Monthpiecehere
A team of Northwestern University engineers has created a new way to print three-dimensional metallic objects using rust and metal powders.
While current methods rely on vast metal powder beds and expensive lasers or electron beams, Northwestern’s new technique uses liquid inks and common furnaces, resulting in a cheaper, faster, and more uniform process. The Northwestern team also demonstrated that the new method works for an extensive variety of metals, metal mixtures, alloys, and metal oxides and compounds.
“This is exciting because most advanced manufacturing methods being used for metallic printing are limited as far as which metals and alloys can be printed and what types of architecture can be created,” said Ramille Shah, assistant professor of materials science and engineering at Northwestern’s McCormick School of Engineering and of surgery in the Feinberg School of Medicine, who led the study. “Our method greatly expands the architectures and metals we’re able to print, which really opens the door for a lot of different applications.”
Energy-harvesting magnets that change their volume when placed in a magnetic field have been discovered by US researchers. The materials described by Harsh Deep Chopra of Temple University and Manfred Wuttig of the University of Maryland produce negligible waste heat in the process and could displace current technologies and lead to new ones, such as omnidirectional actuators for mechanical devices and microelectromechanical systems (MEMS). [Nature, 2015, 521, 340-343; DOI:10.1038/nature14459]
All magnets change their shape but not their volume, even auxetic magnets were previously characterized on the basis of volume conserving Joule magnetostriction. This fundamental principle of volume conservation has remained unchanged for 175 years, since the 1840s, when physicist James Prescott Joule found that iron-based magnetic materials would elongate and constrict anisotropically but not change their volume when placed in a magnetic field, so-called Joule magnetostriction.
The work of Chopra, Wuttig changes that observation fundamentally with the demonstration of volume-expanding magnetism. “Our findings fundamentally change the way we think about a certain type of magnetism that has been in place since 1841,” explains Chopra. “We have discovered a new class of magnets, which we call ‘Non-Joulian Magnets,’ that show a large volume change in magnetic fields.” Chopra described the phenomenon to us: “When ‘excited’ by a magnetic field, they swell up like a puffer fish,” he says.
According to Dictionary.com, steel is “any of various modified forms of iron, artificially produced, having a carbon content less than that of pig iron and more than that of wrought iron, and having qualities of hardness, elasticity, and strength varying according to composition and heat treatment: generally categorized as having a high, medium, or low-carbon content”.
Perhaps the most well known alloy around, as well as one of the most common materials in the world, steel is essentially iron with a small percentage of carbon (and, on occasion, one or more other elements). Not enough carbon and you’re stuck with wrought iron, too much carbon and you get cast iron. The graph above is a binary iron-carbon phase diagram that goes from zero percent carbon to about 6.5 percent, illustrating the various phases that can form.
Steel has been known about since ancient times, some pieces dating back to 1800 BC, but it was the invention of the Bessemer process during the industrial revolution that really popularized the alloy. (Technically, similar methods had been used before, particularly in China and Japan, but Henry Bessemer invented the modern method, industrializing it and obtaining a patent in 1856.)
Mainly used in construction, the alloy has been used for almost every possible application: from office furniture to steel wool, from bulldozers to washing machines, and from wires to watches, the possibilities are pretty much endless. Steel is also one of the world’s most-recycled materials, able to be used more than once, with a recycling rate of over 60% globally.
The addition of carbon allows the steel to be stronger than the iron it’s made from. Adding nickel and manganese increases its tensile strength, chromium increases hardness and melting temperature, and vanadium also increases hardness while making it less prone to metal fatigue. Stainless steel has at least eleven percent chromium, whereas Hadfield steel (which resists wearing) contains twelve to fourteen percent manganese. Check out theselinks for more information on the effects of adding certain elements.
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.
Though not a commercially available alloying element, largely due to its cost, the effects of the addition of ruthenium to steel have been considered and researched. In general, the addition of small amounts of ruthenium (and other platinum group metals, such as palladium) has been found to increase the corrosion resistance of certain stainless steels, especially in non-oxidizing environments.
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