The mechanism of pack RE\|chrome\|boronizing and the effects of RE and Cr elements on the formation of RE\|chrome\|boroinized layer were studied by the aid of thermodynamic calculations and the layers compositions analyses in this paper.The results show that boronizing plays a leading role in pack ER\|chrome\|boronizing because active RE and Cr atoms are obtained by reducing the solid materials,and then RE and Cr atoms dissolve in the RE\|chrome\|boronized layer,be fine and close (Fe,Cr,RE)\-2B phase in texture,by way of passing the grain boundary chiefly and replacement\|spreading separately.The spreading of RE and Cr atoms plays an important role in forming the fine columnar grains and decreasing surface\|layer voids of RE\|chrome boronized layer.
