A new alloy actually contracts when heated rather than expands. This unusual outcome, called negative thermal expansion, is reported in "Negative thermal expansion materials: technological key for control of thermal expansion,” found in a recent issue ofScience and Technology of Advanced Materials, by Koshi Takenaka at the Department of Crystalline Materials Science, Nagoya University in Nagoya, Japan.

Invar, or FeNi36, is an iron-nickel alloy that lacks expansion or contraction with temperature changes. This type of material is important now in controlling thermal expansion of composites in nanometer-size electronic circuits and is significant in the future production of products such as fuel cells and thermoelectric devices. Invar gives researchers a highly stable material for precision instruments, clocks or seismic creep gauges.

"NTE materials will expand our capability of thermal-expansion control, opening a new paradigm of materials science and technology thermal-expansion-adjustable composites,” Takenaka notes in his paper.

Read more from the National Institute for Materials Science in Tsukuba, Japan, at http://pdf.japancorp.net/english/clientreports/4184/210.pdf.