Editing Metal (section)

===Brittle elemental metal===
While nearly all elemental metals are malleable or ductile, a few—beryllium, chromium, manganese, gallium, and bismuth—are brittle.<ref>{{cite book |title=Structure–Property Relations in Nonferrous Metals |last1=Russell |first1=A. M. |last2=Lee |first2=K. L. |year=2005 |publisher=John Wiley & Sons |location=Hoboken, NJ |isbn=978-0-471-64952-6 |pages=passim |bibcode=2005srnm.book.....R}}</ref> Arsenic and antimony, if admitted as metals, are brittle. Low values of the ratio of bulk [[elastic modulus]] to [[shear modulus]] ([[Pugh's criterion]]) are indicative of intrinsic brittleness.<ref>{{Cite journal |last1=Senkov |first1=O. N. |last2=Miracle |first2=D. B. |date=2021-02-25 |title=Generalization of intrinsic ductile-to-brittle criteria by Pugh and Pettifor for materials with a cubic crystal structure |journal=Scientific Reports |language=en |volume=11 |issue=1 |page=4531 |doi=10.1038/s41598-021-83953-z |issn=2045-2322 |pmc=7907099 |pmid=33633140|bibcode=2021NatSR..11.4531S }}</ref> A material is brittle if it is hard for dislocations to move, which is often associated with large [[Burgers vector]]s and only a limited number of slip planes.<ref>{{Cite book |url=https://linkinghub.elsevier.com/retrieve/pii/B9780750646819X50007 |title=Introduction to Dislocations |date=2001 |publisher=Elsevier |isbn=978-0-7506-4681-9 |language=en |doi=10.1016/b978-0-7506-4681-9.x5000-7}}</ref>