This blog consists of daily news items of interest to followers of QUIDDITY as a qualitatitive method of describing the world. This approach was described by Clive Barker in "The Great and Secret Show" and analyzed in the 149 posts of the QUIDDITY blog of this writer (see link to companion blog).
Thursday, December 24, 2015
Magnesium nanoparticle alloy
UCLA Researchers Create Exceptionally
Strong and Lightweight New Metal Magnesium infused
with dense silicon carbide nanoparticles could be used for airplanes, cars,
mobile electronics and more
By Matthew Chin -- December 23, 2015
At left, a deformed sample of pure
metal; at right, the strong new metal made of magnesium with silicon carbide
nanoparticles. Each central micropillar is about 4 micrometers across.
A team led by researchers from the UCLA Henry Samueli School
of Engineering and Applied Science has created a super-strong yet light
structural metal with extremely high specific strength and modulus, or
stiffness-to-weight ratio. The new metal is composed of magnesium infused with
a dense and even dispersal of ceramic silicon carbide nanoparticles. It could
be used to make lighter airplanes, spacecraft, and cars, helping to improve
fuel efficiency, as well as in mobile electronics and biomedical devices.
To create the super-strong but lightweight metal, the team
found a new way to disperse and stabilize nanoparticles in molten metals. They
also developed a scalable manufacturing method that could pave the way for more
high-performance lightweight metals. The research was published today in
“It’s been proposed that nanoparticles could really enhance
the strength of metals without damaging their plasticity, especially light
metals like magnesium, but no groups have been able to disperse ceramic
nanoparticles in molten metals until now,” said Xiaochun Li, the principal
investigator on the research and Raytheon Chair in Manufacturing Engineering at
UCLA. “With an infusion of physics and materials processing, our method paves a
new way to enhance the performance of many different kinds of metals by evenly
infusing dense nanoparticles to enhance the performance of metals to meet
energy and sustainability challenges in today’s society.”
Structural metals are load-bearing metals; they are used in
buildings and vehicles. Magnesium, at just two-thirds the density of aluminum,
is the lightest structural metal. Silicon carbide is an ultra-hard ceramic
commonly used in industrial cutting blades. The researchers’ technique of
infusing a large number of silicon carbide particles smaller than 100
nanometers into magnesium added significant strength, stiffness, plasticity and
durability under high temperatures.
The researchers’ new silicon carbide-infused magnesium
demonstrated record levels of specific strength — how much weight a material
can withstand before breaking — and specific modulus — the material’s stiffness-to-weight
ratio. It also showed superior stability at high temperatures.
Ceramic particles have long been considered as a potential
way to make metals stronger. However, with microscale ceramic particles, the
infusion process results in a loss of plasticity.
Nanoscale particles, by contrast, can enhance strength while
maintaining or even improving metals’ plasticity. But nanoscale ceramic
particles tend to clump together rather than dispersing evenly, due to the
tendency of small particles to attract one other.
To counteract this issue, researchers dispersed the
particles into a molten magnesium zinc alloy. The newly discovered nanoparticle
dispersion relies on the kinetic energy in the particles’ movement. This
stabilizes the particles’ dispersion and prevents clumping.
To further enhance the new metal’s strength, the researchers
used a technique called high-pressure torsion to compress it.
“The results we obtained so far are just scratching the
surface of the hidden treasure for a new class of metals with revolutionary
properties and functionalities,” Li said.
The new metal (more accurately called a metal nanocomposite)
is about 14 percent silicon carbide nanoparticles and 86 percent magnesium. The
researchers noted that magnesium is an abundant resource and that scaling up
its use would not cause environmental damage.
The paper’s lead author is Lian-Yi Chen, who conducted the
research as a postdoctoral scholar in Li’s Scifacturing Laboratory at UCLA.
Chen is now an assistant professor of mechanical and aerospace engineering at
Missouri University of Science and Technology.
The paper’s other authors from UCLA include Jia-Quan Xu, a
graduate student in materials science and engineering; Marta Pozuelo, an
assistant development engineer; and Jenn-Ming Yang, professor of materials
science and engineering.
The other authors on the paper are Hongseok Choi, of ClemsonUniversity;
Xiaolong Ma, of North CarolinaStateUniversity;
Sanjit Bhowmick of Hysitron, Inc. of Minneapolis;
and Suveen Mathaudhu of UC Riverside.
The research was funded in part by the National Institute of
Standards and Technology.