654877bd_erials_Science_and_Engineering__Significance
[Date] 1991 [Candidate Moment] Sumio Iijima discovers nanotubes, carbon atoms arranged in tubular structures. [Significance] 
Creates expectations of important structural and nonstructural applications as nanotubes are about 100 times stronger than steel at just a sixth of the weight while also possessing unusual heat and conductivity characteristics.
Greatest Moments in Materials Science and Engineering
Significance