1[4]J. Peng, H.Dong, T.Bell, F.Chen, Z.Mo, C.Wang and Q.Peng: Effect of rare earth elements on plasma nitriding of 38CrMoAl steel. Surface Engineer, 1996,12, (2), pp. 147-151.
2[5]J. Zhang, D. P. Cleugh, P. Buchhagen, B. Lee, Y. Sun,Some Experimental observation on Rare Earth Plasma Nitriding , Proceedings of ICSE'99, Wuhan, China,1999.10
