1. Iron, manganese and nickel are the main added elements in aluminium bronze. Therefore, complex aluminium bronzes include Cu-Al-Fe, Cu-AI-Mn, Cu-Al-Fe-Mn, Cu-AlFe-Ni and Cu-Al-Fe-Mn-Ni systems.
2. Iron is added to the Cu-AI alloy to inhibit the decomposition of →a plus 2 and prevent embrittlement caused by spontan annealing. Adding a certain amount of iron can form fine FeAl3 particles, which can serve as non-spontan crystal nuclei of the a phase and refine the a grains in the as-cast structure.
3. Manganese has a large solubility in Cu-AI alloy, which can cause solid solution strengthening. A more important function is to inhibit spontaneous annealing. The addition of manganese has no obvious effect on the structural characteristics of aluminum bronze.
4. The main function of nickel is to improve the mechanical properties, thermal strength and corrosion resistance of the alloy. Nickel is mainly added to aluminum-iron bronze. In addition to dissolving into solid solution (a and ), it can also form K phase. This phase is a Ni-Fe-Al compound with an ordered body-centered cubic lattice, and its structure is similar to NiAI and FeAl. The content and mutual proportion of aluminum, iron and nickel in the alloy, as well as the heat treatment conditions of the alloy, all affect the K phase precipitation morphology and the performance of the alloy.
5. When the nickel content is greater than the iron content, the K phase will be in the form of lamellae, and when the nickel content is less than the iron content, the K phase will precipitate in the form of blocks. Only when the iron and nickel contents are roughly equal, the K phase precipitates in the form of fine particles. This structure is beneficial to the mechanical properties of the aloi.
6. Iron, manganese and nickel are the main added elements in aluminum bronze. Therefore, complex aluminum bronzes include Cu-Al-Fe, Cu-AI-Mn, Cu-Al-Fe-Mn, Cu-AlFe-Ni and Cu-Al-Fe-Mn-Ni systems.