Details
| Original language | English |
|---|---|
| Pages (from-to) | 7683-7694 |
| Number of pages | 12 |
| Journal | Acta materialia |
| Volume | 59 |
| Issue number | 20 |
| Publication status | Published - 15 Oct 2011 |
| Externally published | Yes |
Abstract
The influence of surface modification by internal oxidation on dry sliding wear behavior of ultrafine-grained (UFG) Nb-Zr was investigated using a pin-on-disc type tribometer. The results show that improvement in strength by grain refinement via equal-channel angular pressing/extrusion has no substantial effect on the wear resistance of the non-oxidized UFG samples as compared to the coarse-grained material. This was attributed to the complex wear mechanisms operating in this alloy, such as adhesion leading to smearing, tribo-chemical reactions resulting in strong oxidative wear and also abrasion bringing about scratches and deep grooves. However, internal oxidation by heat-treatment significantly improved the wear resistance of Nb-Zr, especially under low to medium applied pressures due to the hardened diffusion zone with ZrO2 nanoparticles formed in the subsurface layer. Moreover, the improvement was more pronounced in the UFG material, which is attributed to increased diffusion in the UFG microstructure. When the applied pressure was increased above 0.5 MPa, however, the wear rate increased considerably due to the elimination of the hardened subsurface layer. Still, even under high pressures, the oxidized samples demonstrated lower weight loss as compared to non-oxidized samples. Based on the investigations of the worn surfaces, it was determined that internal oxidation mostly eliminates the complex wear mechanisms operational in the non-oxidized samples, especially under low/medium loads. Improvement in wear properties by internal oxidation along with enhanced mechanical properties and previously demonstrated good biocompatibility and superior fatigue performance make internally oxidized UFG NbZr a promising candidate for biomedical applications in the human body.
Keywords
- Niobium-zirconium alloys, Severe plastic deformation, Thermal oxidation, Ultrafine-grained materials, Wear behavior
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Ceramics and Composites
- Materials Science(all)
- Polymers and Plastics
- Materials Science(all)
- Metals and Alloys
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In: Acta materialia, Vol. 59, No. 20, 15.10.2011, p. 7683-7694.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Effect of internal oxidation on wear behavior of ultrafine-grained Nb-Zr
AU - Purcek, G.
AU - Saray, O.
AU - Rubitschek, F.
AU - Niendorf, T.
AU - Maier, H. J.
AU - Karaman, I.
N1 - Funding information: G.P. acknowledges support from Scientific Research Projects of Karadeniz Technical University, Turkey, under Grant No. 2009.112.003.1, and TUBITAK, Turkey, under 2219-International Postdoctoral Research Scholar Program. I.K. acknowledges support from the National Science Foundation, International Materials Institutes Program through Grant No. DMR 08-44082, Office of Specific Programs, Division of Materials Research, Arlington, VA, USA. Financial support by Deutsche Forschungsgemeinschaft is also gratefully acknowledged.
PY - 2011/10/15
Y1 - 2011/10/15
N2 - The influence of surface modification by internal oxidation on dry sliding wear behavior of ultrafine-grained (UFG) Nb-Zr was investigated using a pin-on-disc type tribometer. The results show that improvement in strength by grain refinement via equal-channel angular pressing/extrusion has no substantial effect on the wear resistance of the non-oxidized UFG samples as compared to the coarse-grained material. This was attributed to the complex wear mechanisms operating in this alloy, such as adhesion leading to smearing, tribo-chemical reactions resulting in strong oxidative wear and also abrasion bringing about scratches and deep grooves. However, internal oxidation by heat-treatment significantly improved the wear resistance of Nb-Zr, especially under low to medium applied pressures due to the hardened diffusion zone with ZrO2 nanoparticles formed in the subsurface layer. Moreover, the improvement was more pronounced in the UFG material, which is attributed to increased diffusion in the UFG microstructure. When the applied pressure was increased above 0.5 MPa, however, the wear rate increased considerably due to the elimination of the hardened subsurface layer. Still, even under high pressures, the oxidized samples demonstrated lower weight loss as compared to non-oxidized samples. Based on the investigations of the worn surfaces, it was determined that internal oxidation mostly eliminates the complex wear mechanisms operational in the non-oxidized samples, especially under low/medium loads. Improvement in wear properties by internal oxidation along with enhanced mechanical properties and previously demonstrated good biocompatibility and superior fatigue performance make internally oxidized UFG NbZr a promising candidate for biomedical applications in the human body.
AB - The influence of surface modification by internal oxidation on dry sliding wear behavior of ultrafine-grained (UFG) Nb-Zr was investigated using a pin-on-disc type tribometer. The results show that improvement in strength by grain refinement via equal-channel angular pressing/extrusion has no substantial effect on the wear resistance of the non-oxidized UFG samples as compared to the coarse-grained material. This was attributed to the complex wear mechanisms operating in this alloy, such as adhesion leading to smearing, tribo-chemical reactions resulting in strong oxidative wear and also abrasion bringing about scratches and deep grooves. However, internal oxidation by heat-treatment significantly improved the wear resistance of Nb-Zr, especially under low to medium applied pressures due to the hardened diffusion zone with ZrO2 nanoparticles formed in the subsurface layer. Moreover, the improvement was more pronounced in the UFG material, which is attributed to increased diffusion in the UFG microstructure. When the applied pressure was increased above 0.5 MPa, however, the wear rate increased considerably due to the elimination of the hardened subsurface layer. Still, even under high pressures, the oxidized samples demonstrated lower weight loss as compared to non-oxidized samples. Based on the investigations of the worn surfaces, it was determined that internal oxidation mostly eliminates the complex wear mechanisms operational in the non-oxidized samples, especially under low/medium loads. Improvement in wear properties by internal oxidation along with enhanced mechanical properties and previously demonstrated good biocompatibility and superior fatigue performance make internally oxidized UFG NbZr a promising candidate for biomedical applications in the human body.
KW - Niobium-zirconium alloys
KW - Severe plastic deformation
KW - Thermal oxidation
KW - Ultrafine-grained materials
KW - Wear behavior
UR - http://www.scopus.com/inward/record.url?scp=80053963315&partnerID=8YFLogxK
U2 - 10.1016/j.actamat.2011.08.028
DO - 10.1016/j.actamat.2011.08.028
M3 - Article
AN - SCOPUS:80053963315
VL - 59
SP - 7683
EP - 7694
JO - Acta materialia
JF - Acta materialia
SN - 1359-6454
IS - 20
ER -