Of low carbon equivalent gray cast iron modified by rare earth α- The lattice constant of Fe is measured by X-ray diffraction, as shown in the curve after the measurement of low carbon equivalent gray cast iron before and after modification.
According to the data in the figure, the strength of low carbon equivalent gray cast iron is calculated α- Fe lattice constant (as shown in the table). According to the table, after rare earth modification, α- With the increase of Fe lattice constant, when the addition of rare earth reaches 0.1% and 0.3% respectively, the content of low carbon equivalent gray cast iron increases α- The lattice constants of Fe have little difference; When the amount of rare earth is reached, the lattice constant reaches the maximum. In general, the lattice constant of low carbon equivalent gray cast iron inoculated by rare earth is α- The lattice constant of Fe is significantly higher than that before modification α- Fe lattice constant is large. This shows that the addition of rare earth alloy in the smelting process makes the low-carbon equivalent gray cast iron α- The distortion of Fe lattice obviously increases the microhardness of gray cast iron matrix, and then increases the tensile strength of gray cast iron.
| Rare earth alloy addition (%) | Lattice constant (a) | Cell volume (v) |
| 0 | 2.86648 | 23.55A^3 |
| 0.1 | 2.86668 | 23.56A^3 |
| 0.2 | 2.86553 | 23.53A^3 |
| 0.25 | 2.86771 | 23.58A^3 |
| 0.3 | 2.86674 | 23.56A^3 |
In addition, the solid solubility of rare earths in gray cast iron refers to the statistics of rare earths existing in the crystal lattice of cast iron in the solid state, but it does not include the segregation of rare earths at product defects, let alone the amount of rare earths existing in intermetallic compounds. The results obtained by measuring the lattice constant can truly reflect the solid solubility of rare earth elements in cast iron, while other measurement methods can not separate the rare earth existing in inclusions from the rare earth existing in metal state, resulting in high data of solid solubility. The results show that there is still a small amount of rare earth elements in cast iron at high temperature, which is usually less than 0.4%. At room temperature, the amount of rare earth solid solution is lower, about 0.1%.