Microstructure characterization of yttrium-modified reactive-ion-plated Ti(Y)N coating by means of trasmission electron microscopy

Abstract By means of transmission electron microscopy and microdiffraction techniques, the fine microstructure of the Ti(Y)N coating A3 steel substrate system has been revealed to be a series of sublayers of mixed phases: substrate α-Fe; α -Fe + Y 6 Fe 23 (sublayer I); FeTi + Y + Ti (sublayer II); Ti 2 N + YN + Ti x N y (sublayer III); TiN (columnar crystallites). Sublayer I is about 2000 A thick, sublayer II about 500 A and sublayer III about 1200 A. The phases at the interface areas show the following orientation relations: [ 1 23]α-Fe∣[101]Y 6 Fe 23 ∣[01 2 ]FeTi (12 1)α-Fe∣( 1 21)Y 6 Fe 23 ∣( 1 21)FeTi and [ 1 13]FeTiFe∣[0001]Y∣[ 1 11]FeTi (2 1 )∣)( 11 20)Y∣(01 1 Ti 2 N The formation mechanism of the Ti(Y)N/A3 system is also discussed and a structure model is proposed.