Super-strong aluminium alloy invented
However, high-strength, lightweight aluminium alloys with strength comparable to stainless steels would revolutionise the automobile and aerospace industries.
WEST LAFAYETTE, Indiana: Researchers have demonstrated how to create a super-strong aluminium alloy that rivals the strength of stainless steel, an advance with potential industrial applications.
“Most lightweight aluminium alloys are soft and have inherently low mechanical strength, which hinders more widespread industrial application,” said Zhang Xinghang, a professor in Purdue University’s School of Materials Engineering. “However, high-strength, lightweight aluminium alloys with strength comparable to stainless steels would revolutionise the automobile and aerospace industries.”
New research shows how to alter the microstructure of aluminium to impart greater strength and ductility.
Findings were detailed in two new research papers. The work was led by a team of researchers that included Purdue postdoctoral research associate xue Sichuang and doctoral student Li Qiang.
The most recent paper was published online in the journal Advanced Materials. The earlier paper was published in November in the journal Nature Communications.
The new high-strength aluminium is made possible by introducing “stacking faults,” or distortion sin the crystal structure. While these are easy to produce in metals such as copper and silver, they are difficult to introduce in aluminium because of its high “stacking fault energy.”
“It has been shown that twin boundaries are difficult to be introduced into aluminium. The
– Zhang Xinghang, professor of materials engineering
formation of the 9R phase in aluminium is even more difficult because of its high stacking fault energy,” Zhang said.
“You want to introduce both nanotwins and 9R phase in nanograined aluminium to increase strength and ductility and improve thermal stability.”
Now, researchers have learned how to readily achieve this 9R phase and nanotwins in aluminium.
“These results show how to fabricate aluminium alloys that are comparable to, or even stronger than, stainless steels,” he said.
“There is a lot of potential commercial impact in this finding.”
Xue is lead author of the Nature Communications paper, which is the first to report a “shockinduced” 9R phase in aluminium. Researchers bombarded ultrathin aluminium films with tiny micro-projectiles of silicon dioxide, yielding 9R phase.
“Here, by using a laserinduced projectile impact testing technique, we discover a deformation-induced 9R phase with tens of nanometres in width,” Xue said.
The microprojectile tests were performed by a research group at Rice University, led by professor Edwin L. Thomas, a co-author of the Nature Communications paper.
A laser beam causes the particles to be ejected at a velocity of 600 metres per second. The procedure dramatically accelerates screening tests of various alloys for impactresistance applications.
“Say I want to screen many materials within a short time,” Zhang said.
“This method allows us to do that at far lower cost than otherwise possible.”