The second phase of TZM alloy is mainly solid solution, carbides and oxides of Ti and Zr. These second phases have an important effect on the alloy’s mechanical strength, toughness, and creep strength. The second phase will occur alloy’s strengthening effect, such as solid solution strengthening and second phase strengthening. To understand and control the formation, particle size and distribution of second phase for improving the thermal deformation resistance and properties of the alloy has great significance.
Observing the SEM picture found, there are a lot of second phase at grain boundaries of the alloy. In TZM alloy carbon content and oxygen content both are very high, so it is considered that the second phase showing at grain boundaries is Mo2C, Ti and Zr’s oxides and carbides. The reason that a lot of second phases gathering at the grain boundaries is during sintered cooling process Ti, Zr and C reduce the solubility, and thus precipitated to the grain boundaries.
 |
| TZM alloy image |
A large number of second phases at grain boundaries during metals deformation, due to differences in the elastic modulus can not be synchronized deformation, the grains will result from the grain boundaries, so that the second phase crushing, leading to reduce the tensile strength and elongation. It causes the material to break, reduce processing performance and mechanical properties of the material in the subsequent deformation.
The fine distribution second phases in intragranular and grain boundary can improve the recrystallization temperature and the tensile strength of the alloy, having a beneficial effect on the properties of the alloy. While the second phase distribution in the alloy depends on the heat treatment process. If the material can be rapidly cooled during sintering, hardening, so that Ti, Zr, C can be solid solution in the crystal lattice of molybdenum, then after tempering treatment Ti, Zr, C precipitation dispersed in the alloy to improve the properties of the alloy materials.
Tel.: +86 592 5129696/86 592 5129595
Fax: +86 592 5129797
没有评论:
发表评论