Internal carbonitriding behavior of Ni-V, Ni-Cr, and Ni-3Nb alloys
- Metals Technology, Inc., Northridge, CA (United States)
- Univ. of Arizona, Tucson, AZ (United States). Arizona Materials Lab.
Ni-2V, Ni-5V, Ni-12V, Ni-10Cr, Ni-20Cr, and Ni-3Nb alloys were carbonitrided in C{sub 3}H{sub 6} and NH{sub 3} gas mixtures (bal H{sub 2}) over the range 700--1,000 C. Carbonitridation of Ni-12V and Ni-20Cr in C{sub 3}H{sub 6}/NH{sub 3}/H{sub 2} (1.5/1.5/97 v/o) and (1.5/10/88.5 v/o) produced duplex subscales consisting of near-surface nitrides with underlying carbides. Growth of each zone obeyed the parabolic rate law under most conditions. The presence of carbon generally did not effect the depth of the nitride zones compared to nitriding the alloys in NH{sub 3}/H{sub 2} (10/90 v/o). However, at 700 C, the nitride zones were deeper in the carbonitrided Ni-V alloys and Ni-20Cr. The presence of nitrogen generally increased the depth of the carbide zones in Ni-12V and Ni-20Cr compared to carburizing these alloys in C{sub 3}H{sub 6}/H{sub 2} (1.5/98.5 v/o). VN, CrN, and NbN formed in Ni-V, Ni-Cr, and Ni-Nb alloys, respectively, whereas the underlying carbide layers contained V{sub 4}C{sub 3} in Ni-12V, Cr{sub 3}C{sub 2} above a zone of Cr{sub 7}C{sub 3} in Ni-20Cr, and NbC in Ni-3Nb. The solubilities and diffusivities of nitrogen and carbon in nickel were determined. Nitrogen and carbon each exhibited retrograde solubility with temperature in pure Ni in both carbonitriding environments. Nitrogen diffusion in nickel was generally lower in each carbonitriding mixture compared to nitrogen diffusion in a nitriding environment, except at 700 C when nitrogen diffusion was higher. Carbon diffusion in nickel was generally higher in the carbonitriding environments compared to carbon diffusion in a carburizing environment.
- OSTI ID:
- 684338
- Journal Information:
- Oxidation of Metals, Vol. 52, Issue 5-6; Other Information: PBD: Dec 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Internal-nitriding behavior of Ni-V and Ni-3Nb alloys
Permeation of nitrogen in solid nickel and deformation phenomena accompanying internal nitridation