CHARACTERIZATION OF GAMMA'-FE4N PRECIPITATES IN A COMPOUND LAYER FORMED BY AUSTENITIC NITROCARBURIZING TREATMENT

The precipitation of gamma'-Fe4N phase from the epsilon-matrix in a qu enched and aged compound layer of 0.2%C steel formed by austenitic nit rocarburizing treatment has been investigated through transmission ele ctron microscopy. The orientation relationship between the gamma' phas e and the epsilon matrix is determined to be {0001}(epsilon) // {111}( gamma'), and [1 (2) over bar 10](epsilon) // [011](gamma'). The gamma' precipitates appearing in thin plates in the {0001} planes of epsilon matrix are sometimes observed to be 180 degrees related to each other . The mechanism of age-hardening in the compound layer is also discuss ed.