Materials science

LS 59-1 brass (40% zinc, 1% lead, 59% copper) is an alloy with high workability. Various items (sheets, pins, pipes, bushings, nuts, etc.) are obtained from it by casting, rolling and pressing. The microstructure of foundry brass consists of a liquid-colored plastic a -phase and a dark-colored hard and brittle b -phase. b -phase solvent CuZn is a solid solution (Fig. 17.3, a).
An alloy of copper with metals such as tin, aluminum, lead, silicon, beryllium, chromium, antimony, manganese and iron is called bronze . Details of various shapes and sizes are obtained from bronzes by casting method.
Br 010 (10% tin, 90% copper) bronze is used to obtain shaped castings due to its high casting properties. The microstructure of this bronze (Fig. 16.3, b) consists of a non-uniform solid solution ( - solution is a solid solution of tin in copper) and a eutectoid with + S u ₃₁ Sn _{8 composition.} - the dark areas of the solution are rich in copper, and the areas of leakage are rich in tin. The eutectoid phase appears as dark dots.
Aluminum alloys used in engineering are divided into two types: malleable and casting alloys.
Due to its good corrosion resistance and molding properties, Quymabap AL 2 (10...13% silicon, the rest - aluminum) silumin is used to make various details (caps, casings, drums, etc.).
consists of dark crystals of silicon with a larger structure + Si-containing eutectic (Fig. 16.4, a). These structures reduce the plasticity of the alloy. - phase - a solid solution of silicon in aluminum.
If silumin is modified with sodium (state diagram, Fig. 16.5), changes in its crystallization occur (Fig. 16.4, b), that is, silumin with 12% silicon turns into an alloy up to the eutectoid, the structure of which is a liquid-colored plastic phase consists of dark-colored fine-grained eutectic (Fig. 16.4, b). The plasticity and thoroughness of the alloy increases. For example, d _v =14 kgs/mm ² , d=3% for unmodified AL2 silumin , and d _v =18 kgs/mm ² , d=8% for modified silumin.



a) b)

Figure 16.3. a) Microstructure of casting brass LS 59-1. The alloy was treated with a solution of iron chloride in hydrochloric acid, x200;

b ) Microstructure of tin bronze of Br .010. The alloy was treated with a solution of ferric chloride in hydrochloric acid, x100.

Figure 16.4. Microstructure of AL 2 brand silumin: α-unmodified silumin; β-modified silumin. The alloy was treated with a solution of hydrogen chloride in water, x200

Figure 16.5. State diagram of aluminum-silicon system alloys

a) b)

16. Figure 6 . a) Structure of duralumin grade D 1 after aging in water. The alloy was treated with a solution of hydrofluoric acid in water, x 200;

b ) Microstructure of tin babbitt grade B 83. Add nitric acid to the mixture
Treated with a 4% solution in alcohol, x 100.