TiC－50Nb钢结合金相界面组织结构的研究

A Study on the Phase Boundary Structure of Type TiC-50Nb Steel-Bonded Carbide

对ＴｉＣ－５０Ｎｂ钢结合金的相界面组织结构进行了研究，探讨了相界面结合状况。研究表明：Ｔｉ，Ｆｅ在相界面层具有成分梯度；适当增加Ｍｏ元素含量，可在ＴｉＣ，Ｔｉ（Ｃ，Ｎ）硬质相周边获得包覆层组织；ＲＥ呈球状稀土化合物形式存在于ＴｉＣ／钢基体的相界面上，对界面起净化作用；用高分辨电镜观察到因脱溶物Ｍ＿２Ｃ引起的晶格条纹歪扭，由此产生二次硬化效应。研究结果为建立硬质材料的韧化机制提供了实验依据。

The phase boundary structure of type TiC-50Nb steel-bonded carbide is investigated andthe bonding state at the boundary is discussed.Experimental results show that elements Tiand Fe at the boundary layer exhibit composition gradient.When the content of element Mois increased to a certain amount,a rim structure surrounding the periphery of the TiC and Ti(C,N)grains can be obtained.Rare earth elements existing in the form of spherical com-pound are distributed along the TiC/steel-matrix interface and play the role of purifying theboundary.Crystal lattice distortion due to M2C precipitation has been observed by HREMand the secondary hardening effect of TiC-50Nb steel-based carbide can be explained.All re-sults can provide experimental basis for extablishing hard materials toughening mechanism.