• 
  Negative thermal expansion (NTE) is a physicochemical process, during which various materials contract upon heating rather than expanding. However, if we mix a negative thermal expansion material with a normal material which expands on heatin, we could make zero expansion composite material.
• Invar also called FeNi is an alloy of iron (64%) and nickel (36%) with some carbon and chromium. Due to its low coefficient of thermal expansion at room temperature (about 10^-6 K^-1 in length) it is used in precision instruments like clocks, physics laboratory devices, seismic creep gauges, shadow-mask frames etc.