带有马氏体渗碳体层的Fe-Nb合金中温内耗

通过对A_1点以下温度的氢-苯混合气流处理,使研究的Fe-Nb合金丝试样渗入0.5%C.淬火样品的金相观测表明,～40μm厚的样品表面渗碳层为马氏体,渗碳层下部为α-Fe相.用NHI-12型真空K(?)氏摆测量淬火试样的室温内耗和淬火-变形试样的室温-中温内耗发现:淬火样品有一高度达1×10~(-2)的45℃附近峰;而在变形样里则代之出现峰更高(1.7～2.0×10~(-2))的45～60℃内耗峰,还出现两个小内耗峰,即～300℃峰和～235℃峰.分析可知,它们分别是在实验(试样存在很强的宏观组织应力)条件下,马氏体bct晶格中C原子扩散运动峰、亚稳碳化物溶解过程SKK峰和变形α-Fe相的SK...

Medium-Temperature Internal Friction of Fe-Nb Alloys with Martensitic Surface Layer Carbonized

The tested wire specimens of Fe-Nb alloys were carbonized with 0.5wt%C in a hydrogen-benzene mixed gasflow at a temperature lower than A1 point. The metallograph observation on the quenched specimens showed that the structure of the carbonzied surface layer with a thickness about 40μm is martensite, whereas that inside the layer is α-Fe phase. The internal frictions of both the quenched specimens at room temperatures and the quenched-deformed specimens at the room-medium temperatures were measured by NHI-12 vacuum Ke?-pentulum. It was found that there is an 1 × 10^-2 high peak near 45°C in the quenched specimens, while in the quenched-deformed specimens, a higher peak (h = 1.7-2.0 × 10^-2) by 45-60°C takes place with two small peaks, i.e., -300°C and -235°C peaks. It is considered that under the experimental conditions including the strongly macrostrutural stress, they are separately the diffusion peak of carbon atoms in body-centered tetragonal (bct) lattice, the SKK peak in the desolution process of metastable carbide in martensite and the SKK peak of the α-Fe deformed phase.