Editing Superlattice (section)

== Mechanical properties ==

J.S. Koehler theoretically predicted<ref>{{Cite journal | last1 = Koehler | first1 = J. | title = Attempt to Design a Strong Solid | doi = 10.1103/PhysRevB.2.547 | journal = Physical Review B | volume = 2 | issue = 2 | pages = 547–551 | year = 1970 |bibcode = 1970PhRvB...2..547K }}</ref> that by using alternate (nano-)layers of materials with high and low elastic constants, shearing resistance is improved by up to 100 times as the [[Frank–Read Source|Frank–Read source]] of [[dislocation]]s cannot operate in the nanolayers.

The increased mechanical [[hardness]] of such superlattice materials was confirmed firstly by Lehoczky in 1978 on Al-Cu and Al-Ag,<ref>{{cite journal|last1=Lehoczky|first1=S. L.|title=Retardation of dislocation generation and motion in thin-layered metal laminates|journal=Acta Metallurgica|date=1973|volume=41|issue=26|page=1814}}</ref> and later on by several others, such as Barnett and Sproul<ref>{{cite journal | last1=Yashar | first1=P. | last2=Barnett | first2=S. A. | last3=Rechner | first3=J. | last4=Sproul | first4=W. D. | title=Structure and mechanical properties of polycrystalline CrN/TiN superlattices | journal=Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films | publisher=American Vacuum Society | volume=16 | issue=5 | year=1998 | issn=0734-2101 | doi=10.1116/1.581439 | pages=2913–2918| bibcode=1998JVSTA..16.2913Y }}</ref> on hard [[Physical vapor deposition|PVD]] coatings.