Oxidation - Nitridation of Ni-Cr-Al alloys
A series of alloys containing 24-36 wt pct Cr and 13.5 - 25.0 wt pct Al was reacted with air at 1100°C for 260 h. The products of isothermal reaction were scales of a-Al2O3 plus small amounts of Cr2O3. These grew according to parabolic kinetics, interrupted by episodic weight losses caused by partia...
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| Format: | Article |
| Language: | English |
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Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
2004-03-01
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| Series: | Materials Research |
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| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392004000100003 |
| _version_ | 1818149483129602048 |
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| author | Susan Han David John Young |
| author_facet | Susan Han David John Young |
| author_sort | Susan Han |
| collection | DOAJ |
| description | A series of alloys containing 24-36 wt pct Cr and 13.5 - 25.0 wt pct Al was reacted with air at 1100°C for 260 h. The products of isothermal reaction were scales of a-Al2O3 plus small amounts of Cr2O3. These grew according to parabolic kinetics, interrupted by episodic weight losses caused by partial spallation. No nitridation occurred during the isothermal exposures. Reaction during thermal cycling for up to 260 one hour cycles was much more severe. Repeated scale spallation led to subsurface alloy depletion in aluminium and, to a lesser extent, chromium. This caused transformation of the prior alloy three-phase structures (a-Cr+b-NiAl+g-Ni) to single-phase g-nickel solution. Destruction of the external scale allowed gas access to this metal which was able to dissolve both oxygen and nitrogen. Inward diffusion of the two oxidants led to development of a complex internal precipitation zone: Al2O3 and Cr2O3 beneath the surface, then Al2O3 then AIN, then AIN + Cr2N and finally AIN alone in the deepest region. Diffusion-controlled kinetics were in effect initially, but mechanical damage to the internal precipitation zone led to more rapid gas access and approximately linear kinetics in the long term. |
| first_indexed | 2024-12-11T13:07:45Z |
| format | Article |
| id | doaj.art-b12a88cc0d9e4135959ed161c392fa5f |
| institution | Directory Open Access Journal |
| issn | 1516-1439 |
| language | English |
| last_indexed | 2024-12-11T13:07:45Z |
| publishDate | 2004-03-01 |
| publisher | Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol) |
| record_format | Article |
| series | Materials Research |
| spelling | doaj.art-b12a88cc0d9e4135959ed161c392fa5f2022-12-22T01:06:17ZengAssociação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)Materials Research1516-14392004-03-0171111610.1590/S1516-14392004000100003Oxidation - Nitridation of Ni-Cr-Al alloysSusan HanDavid John YoungA series of alloys containing 24-36 wt pct Cr and 13.5 - 25.0 wt pct Al was reacted with air at 1100°C for 260 h. The products of isothermal reaction were scales of a-Al2O3 plus small amounts of Cr2O3. These grew according to parabolic kinetics, interrupted by episodic weight losses caused by partial spallation. No nitridation occurred during the isothermal exposures. Reaction during thermal cycling for up to 260 one hour cycles was much more severe. Repeated scale spallation led to subsurface alloy depletion in aluminium and, to a lesser extent, chromium. This caused transformation of the prior alloy three-phase structures (a-Cr+b-NiAl+g-Ni) to single-phase g-nickel solution. Destruction of the external scale allowed gas access to this metal which was able to dissolve both oxygen and nitrogen. Inward diffusion of the two oxidants led to development of a complex internal precipitation zone: Al2O3 and Cr2O3 beneath the surface, then Al2O3 then AIN, then AIN + Cr2N and finally AIN alone in the deepest region. Diffusion-controlled kinetics were in effect initially, but mechanical damage to the internal precipitation zone led to more rapid gas access and approximately linear kinetics in the long term.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392004000100003Thermal cyclingDiffusionPrecipitationSolubility productNi-Cr-Al alloysAir |
| spellingShingle | Susan Han David John Young Oxidation - Nitridation of Ni-Cr-Al alloys Materials Research Thermal cycling Diffusion Precipitation Solubility product Ni-Cr-Al alloys Air |
| title | Oxidation - Nitridation of Ni-Cr-Al alloys |
| title_full | Oxidation - Nitridation of Ni-Cr-Al alloys |
| title_fullStr | Oxidation - Nitridation of Ni-Cr-Al alloys |
| title_full_unstemmed | Oxidation - Nitridation of Ni-Cr-Al alloys |
| title_short | Oxidation - Nitridation of Ni-Cr-Al alloys |
| title_sort | oxidation nitridation of ni cr al alloys |
| topic | Thermal cycling Diffusion Precipitation Solubility product Ni-Cr-Al alloys Air |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392004000100003 |
| work_keys_str_mv | AT susanhan oxidationnitridationofnicralalloys AT davidjohnyoung oxidationnitridationofnicralalloys |