Effect of Sigma Phase in Co-29Cr-6Mo Alloy on Corrosion Behavior in Saline Solution

Effect of the sigma () phase in Co-29Cr-6Mo alloy on corrosion behavior in saline solution has been investigated. The area fraction of the phase contained in Co-29Cr-6Mo alloy varies depending on the aging time at 1023 K. The phase is mainly observed at grain boundaries. The area fraction of the phase increases with increasing aging time and reaches 0.6% after aging at 1023 K for 21.6 ks. The Co-29Cr-6Mo alloys aged at 1023 K for various aging times were immersed in saline solution at 310 K for 1 week and metal ions released from the alloys were examined by inductively coupled plasma atomic emission spectrometer (ICP-AES). The quantity of a released Co ion does not depend on the aging time and shows almost the same value regardless of the different area fraction of the phase, while that of released Cr, Mo and Ni ions increases with increasing area fraction of the phase. Results of polarization test in saline solution at 310 K revealed that passive current density and breakdown potential of Co-29Cr-6Mo alloys aged at 1023 K for various aging times exhibit almost the same values, although the alloys have different area fraction of the phase. These results suggest that a small amount of the phase (<0:6%) hardly affect the formation and breakdown of passive film in the Co-29Cr-6Mo alloy aged at 1023 K

Deformation and Fracture Behaviors in a Biomedical Co-29Cr-6Mo-0.14 N Alloy Analyzed by X-Ray Tomography

International audienceno abstrac

The damage process in a biomedical Co―29Cr―6Mo―0.14 N alloy analyzed by X-ray tomography and electron backscattered diffraction

International audienceno abstrac

CoCrMo cellular structures made by Electron Beam Melting studied by local tomography and finite element modelling

International audienceno abstrac

Room-temperature ductility of Ti-6Al-4V alloy with alpha ` martensite microstructure

International audienceThe microstructures, cold-rolling abilities, and mechanical properties of a Ti-6Al-4V alloy with a alpha' microstructure were examined, and compared with these properties in alloys with the (alpha+beta) microstructure. The microstructure of a Ti-6Al-4V alloy solution treated at 1373 K followed by quenching (referred to as 1373 K STQ in the following) exhibits the acicular alpha' martensite microstructure. The alloy exhibits the (equilibrium alpha+alpha' martensite) bimodal microstructure when 1223 K solution treatment is carried out followed by quenching (referred to as 1223 K STQ). In contrast, Ti-6Al-4V alloys heat treated at 1373 K or 1223 K, followed by furnace cooling (referred to as 1373 K ST-FC and 1223 K ST-FC), exhibit a lamellar (alpha+beta) microstructure and an equiaxed (alpha+beta) microstructure, respectively. The strength of the STQ specimens was found to be higher than that of the ST-FC specimens. The 1223 K STQ specimen had excellent cold-rolling ability (more than 40% reduction) and higher tensile ductility than those of the ST-FC specimens. The excellent ductility of 1223 K STQ is thought to be due to the constituent phase of the single HCP phase (alpha' and alpha) and the fine equiaxed bimodal morphology. The compositional distribution of the V content enrichment and the decrease in the Al content in the alpha' martensitic region during solution treatment at 1223 K should contribute to the excellent ductility. This work therefore suggests a useful method for improving room-temperature ductility by using industrial Ti-6Al-4V alloys with the alpha' martensite microstructure. (C) 2010 Elsevier B.V. All rights reserved

Microstructure and Mechanical Properties of α’Martensite Type Ti-V-Al Alloy after Cold-or Hot Working Process

International audienceno abstrac

Room-temperature ductility of Ti―6Al―4V alloy with α′ martensite microstructure

International audienceno abstrac