June_AMP_Digital

13 / 78

A D V A N C E D
M A T E R I A L S
&
P R O C E S S E S | J U N E
2 0 1 6
1 3
PROCESS TECHNOLOGY
Martin Thuo with a vial of liquid-metal particles. Courtesy of Christopher Gannon.
SOLDERING METHOD KEEPS
ITS COOL
Researchers at Iowa State Uni-
versity, Ames, demonstrated a method
of producing microscale, liquid-metal
particles for use in heat-free soldering
and material healing at room tempera-
ture. Scientists have long used a meth-
od called undercooling—in which liq-
uid metal is prevented from returning
to a solid state even below its melting
point—to study metal structure and
processing. However, producing large
and stable quantities of undercooled
metals has proved challenging. The
team hypothesized that covering tiny
droplets of liquid metal with a thin,
uniform coating could result in stable
particles of undercooled liquid metal.
Using a high-speed rotary tool, they
sheered liquid metal into droplets with-
in an acidic liquid, then exposed the
particles to oxygen, forming an oxida-
tion layer that encapsulated the liquid
Shuting Lei is working on better ways to
machine ultrathin precision parts.
BRIEF
Constellium N.V., the Netherlands, opened the Constellium University Technol-
ogy Center (UTC) at Brunel University, UK, to design, develop, and prototype
aluminum alloys and automotive structural components. The new center will
feature industrial-size aluminum casting and extrusion equipment as well as
rapid prototyping, which is expected to reduce development time by at least
50% for the advanced alloys used in automotive lightweighting.
.
metal. Researchers proved the concept
by creating liquid-metal particles 10 µm
in diameter containing Field’s metal (an
alloy of bismuth, indium, and tin) as
well as particles of the same size con-
taining an alloy of bismuth and tin.
Martin Thuo, assistant professor of
materials science and engineering, says
the project is a good example of “frugal
innovation,” a guiding principal for his
lab, which strives to solve problems
using the fewest resources. The team
demonstrated healing damaged surfac-
es and joining metals at room tempera-
ture without high-tech instrumenta-
tion, complex material preparation, or a
high temperature process. .
MACHINING BRITTLE
MATERIALS WITH CRACK
CONTROL
Shuting Lei, professor of indus-
trial and manufacturing systems en-
gineering at Kansas State University,
Manhattan, received a $300,000 grant
from the National Science Foundation
to develop better methods of machin-
ing ultrathin precision parts. “Precision
parts made from brittle materials such
as glass and ceramics have broad appli-
cations in the health care, biomedical,
energy, and photonics areas,” says Lei.
“A major problem in machining these
materials is random crack propagation
into the work piece. This results in sub-
surface cracks and thus degrades the
strength of the machined parts.” His
award will support development of a
novel machining process that over-
comes this limitation using controlled
crack propagation. The new method
will enable high-efficiency machining of
brittle materials without compromising
part quality. .