| Abstract: | | 1. |
During nitriding of nickel alloys which contain Ti in the temperature interval from 1000–1200°C for 5–15 h, the conditions are created for the formation of only internal nitriding and the formation of a nitride zone does not occur. These are prerequisites for increased heat resistance.
| | 2. |
In nickel alloys containing a higher concentration of chromium, a zone of internal nitriding of large thickness occurs during the nitriding process. At the most intense levels of nitriding (t=1200°C and  =15h) a through saturation of a 1.5-mm-thick sample of high chrome alloy 2 occurs.
| | 3. |
As a result of nitriding nickel alloys which contain additions of titanium, there is an increase in strength due to the formation of dispersed particles of titanium nitride within the matrix. These particles inhibit the high temperature plastic flow. Another factor which increases the heat resistance of these alloys is the solubility of nitrogen in the matrix which increases the recrystallization temperature, and consequently, the high temperature strength.
| | 4. |
In the alloy which contained the greater concentration of Cr, there is a more intense growth of the diffusion layer. On the other hand, the high concentration of Cr, the lower concentration of Ti, and the absence of Co are the reasons there is a lower increase in the heat resistance as a result of nitriding.
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Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 19–24, June, 1989. |
