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The Structure and Properties of Magnetron Sputtered Fe‐Cr‐Ni Coatings Containing Sigma Phase
Author(s) -
Mallia Bertram,
Dahm Karl L.,
Ogwu Abraham,
Dearnley Peter A.
Publication year - 2007
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.200730501
Subject(s) - materials science , coating , brittleness , indentation hardness , metallurgy , alloy , composite material , porosity , phase (matter) , sputter deposition , cavity magnetron , sputtering , microstructure , thin film , nanotechnology , chemistry , organic chemistry
Fe‐Cr‐Ni alloy coatings were codeposited onto AISI 316L substrates using unbalanced magnetron sputtering. These were: (i) type B1, Fe‐40Cr‐4.5Ni; (ii) type B2, Fe‐38Cr‐8Ni; and (iii) type B3, Fe‐55Cr‐2.5Ni. In the as‐deposited state, the B1 and B3 coatings mainly comprised solid solution α –Fe (Cr) and α ′‐Cr (Fe) phases, were fully dense, and had a microhardness of ∼700 kg · mm −2 , while coating B2 entirely comprised FeCrNi σ ‐phase, contained micro‐ or nanometre‐scale porosity, and had a hardness of ∼370 kg · mm −2 . Despite being less hard, the as‐deposited B2 coating displayed resistance to brittle fracture during scratch testing—this phenomenon was attributed to micropore toughening. When coating types B1 and B3 were partially or completely transformed to σ ‐phase (by vacuum heat treatment) brittle fracture took place during scratch testing.