The Application Exploration Of Iron-Nitrogen Powder Metallrugy Materials And Theory Investigation On The Iron-Nitrogen Phase Transformation

The iron-nitrogen powder metallurgy material was synthesized by powder metallurgy method.The sintering atmosphere were NH₃ and the mixture of NH₃ and N₂.The processes of decomposition of NH₃ and reaction of[N]and Fe were analyzed.The technics on influencing rules of preparing nitrides were studied.The physics and mechanics properties of iron-nitrogen powder metallurgy materials sintering in two different atmosphere and temperature were determined respectively.And the elementary application of the iron-nitrogen powder metallurgy material was also attempted in this paper.The results show that the hardness,wear resisting and corrosion resistance properties of iron-nitrogen powder metallurgy material are better than that of iron base powder metallurgy material.Following increasing of sintering temperature,the porosity decreases,the content of nitride increases and make the materials have better mechanical properties.The samples sintering in simple NH₃ atmosphere have better properties. This material could be looking forward to applicating in magnetics domain as a result of the excellent magnetics property of Fe₄N.Introducing the order-parametern,i.e.,the probability of the position vector (1/2,1/2,1/2) of the crystal lattice possessed of the nitrogen atom,and spreading out a thermodynamic potential energy function according toη,this paper is mainly to discuss the relations betweenηand the temperature T by making use of Landau's phenomenological theory.The rational explanation of the transformation rate of Fe4N was given in the paper.The orientation relations of a Fe—γFe₄N phase transformation has been investigated and the emergence of metastable phase has been predicted.The possible shape ofγFe₄N is also discussed by virtue of the point group theory in this paper.