TY - JOUR
T1 - Nanostructured Co-Cr-Fe alloy surface layer fabricated by combination of laser clad and friction stir processing
AU - Li, Ruidi
AU - Yuan, Tiechui
AU - Qiu, Zili
AU - Zhou, Kechao
AU - Li, Jinglong
N1 - Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2014/11/15
Y1 - 2014/11/15
N2 - Friction stir processing (FSP) was carried out on a laser clad Co-Cr-Fe alloy layer in order to transform the coarse laser clad microstructure into nanostructure and improve the mechanical properties. In the microstructure of the laser clad Co-Cr-Fe alloy, coarse brittle carbides precipitated along the grain boundary and formed networks, along which micro-cracks tended to initiate. After FSP, nanostructured surface layers with 20-100. nm grain sizes and 30-65. μm thicknesses were obtained. The coarse network carbides were significantly crushed to nanosize particles uniformly distributed in the nanostructured Co matrix. The plastic layer showed a gradient grain size that ranged from tens of nanometers at the top surface to tens of micrometers at the interior. A large number of the deformation nanotwins were found in the plastic zone which revealed the deformation mechanism. Moreover, FSP enabled the closure of micro-cracks in the laser-clad microstructure. The formation of nanostructures increased the hardness up to 819. Hv, compared with the 490. Hv of the laser parent alloy. The friction coefficients of the laser-clad Co alloy decreased from about 0.35 to 0.1-0.2 after FSP, with enhanced wear performance.
AB - Friction stir processing (FSP) was carried out on a laser clad Co-Cr-Fe alloy layer in order to transform the coarse laser clad microstructure into nanostructure and improve the mechanical properties. In the microstructure of the laser clad Co-Cr-Fe alloy, coarse brittle carbides precipitated along the grain boundary and formed networks, along which micro-cracks tended to initiate. After FSP, nanostructured surface layers with 20-100. nm grain sizes and 30-65. μm thicknesses were obtained. The coarse network carbides were significantly crushed to nanosize particles uniformly distributed in the nanostructured Co matrix. The plastic layer showed a gradient grain size that ranged from tens of nanometers at the top surface to tens of micrometers at the interior. A large number of the deformation nanotwins were found in the plastic zone which revealed the deformation mechanism. Moreover, FSP enabled the closure of micro-cracks in the laser-clad microstructure. The formation of nanostructures increased the hardness up to 819. Hv, compared with the 490. Hv of the laser parent alloy. The friction coefficients of the laser-clad Co alloy decreased from about 0.35 to 0.1-0.2 after FSP, with enhanced wear performance.
KW - Co-Cr-Fe alloy
KW - Friction stir processing
KW - Laser clad
KW - Microstructure refinement
KW - Severe plastic deformation
UR - http://www.scopus.com/inward/record.url?scp=84912533399&partnerID=8YFLogxK
U2 - 10.1016/j.surfcoat.2014.08.059
DO - 10.1016/j.surfcoat.2014.08.059
M3 - 文章
AN - SCOPUS:84912533399
SN - 0257-8972
VL - 258
SP - 415
EP - 425
JO - Surface and Coatings Technology
JF - Surface and Coatings Technology
ER -