Can Castings Heal Themselves?
The capacity of bones to heal their own cracks has inspired researchers to turn their attention
to cast metals. JOSE MARTINEZ-LUCCI, ANDREW RUZEK, SHOBHIT MISRA, PRADEEP ROHATGI AND RYO AMANO, UNIV. OF WISCONSIN-MILWAUKEE, MILWAUKEE, WISCONSIN
heal cracks in themselves are currently being developed at the University of Wisconsin-Mil- waukee (UWM), Milwaukee. While the technology is in
T
its infancy, the main strategies in the development of self-healing metallic systems have incor- porated shape memory alloy (SMA) reinforcements in cast metals and induced the forma- tion of precipitates in an over- saturated but under-aged alloy.
24 | MODERN CASTING July 2011
hree methods of creating metal castings that can
To put it simply, a material
must have three things to heal itself: a structure that maintains functionality, parts that move to close voids and a trigger to activate this healing action. Te three strat- egies being pursued at UWM are: • incorporating SMA wires in castings;
• using molten interdendritic eutectic to seal surface cracks;
Fig. 1. Shown is an optical microscopy of randomly orientated NiTi fibers in a Sn-20% Bi matrix synthesized at UWM.
• embedding micro-balloons and micro-tubes containing a low melting point alloy in the matrix of a high melting point casting.
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