Quantum effect triggers unusual material expansion
(PHYSorg.com Physics)

You know how you leave space in a water bottle before you pop it in the freezer-to accommodate the fact that water expands as it freezes? Most metal parts in airplanes face the more common opposite problem. At high altitudes (low temperatures) they shrink. To keep such shrinkage from causing major disasters, engineers make airplanes out of composites or alloys, mixing materials that have opposite expansion properties to balance one another out.