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Effect of impurity elements in aluminum alloys
Effect of impurity elements in aluminum alloys
Vanadium VAl11 refractory compounds formed in aluminum alloy, grain refinement effect in the casting process, but the effect is small than titanium and zirconium. Vanadium also has the effect of refining the recrystallization structure and increasing the recrystallization temperature.
Calcium in the aluminum alloy solid solubility is very low, with aluminum to form compounds CaAl4, calcium and is super plasticity of aluminum alloy elements, about 5% calcium and 5% manganese aluminum alloy with super plastic. Calcium and silicon form Ca Si, insoluble in aluminum, due to the decrease of the solid solution of silicon, can slightly improve the electrical conductivity of industrial pure aluminum. Calcium can improve the cutting performance of aluminum alloy. CaSi2 can not heat treatment of aluminum alloy. Trace calcium is beneficial to the removal of hydrogen in the aluminum liquid.
Lead, tin, bismuth element is a low melting point metal, they in aluminum solid solubility small, slightly lower strength of the alloy, but can improve the cutting performance. The addition of bismuth in high magnesium alloy can prevent sodium embitterment.
Antimony is mainly used as a modifier in the cast aluminum alloy, deformation of aluminum alloy is rarely used. Sodium embitterment is only used in the aluminum alloy of Al-Mg deformation.
The structure can improve the beryllium oxide film on the deformation in aluminum alloy; reduce the loss and inclusion casting. Beryllium is a toxic element, can make people produce allergic poisoning. Therefore, contact with food and beverage aluminum alloy can not contain beryllium. The content of beryllium in welding materials is usually controlled at 8 g/ml. Aluminum alloy used as welding matrix should also be controlled by the content of beryllium.
Sodium in aluminum hardly dissolved, the maximum solid solubility less than 0.0025%, the melting point of sodium low (97.8 DEG C), alloy in the presence of sodium, in the solidification process of adsorption in the dendrite surface or grain boundary and thermal processing, grain boundaries of the sodium form liquid adsorption layer, brittle fracture, forming nails compounds, free in the presence of sodium, the sodium embitterment ". When the content of magnesium is over 2%, the magnesium is in the silicon, and the free sodium is released ". Because of the high magnesium alloy does not allow the use of sodium flux. Prevent chlorination method of sodium brittleness and the sodium form NaCl is discharged into a slag and bismuth addition to produce Na2Bi into metal matrix; and antimony generation Na3Sb or adding rare earth can also play the same role.
Calcium in the aluminum alloy solid solubility is very low, with aluminum to form compounds CaAl4, calcium and is super plasticity of aluminum alloy elements, about 5% calcium and 5% manganese aluminum alloy with super plastic. Calcium and silicon form Ca Si, insoluble in aluminum, due to the decrease of the solid solution of silicon, can slightly improve the electrical conductivity of industrial pure aluminum. Calcium can improve the cutting performance of aluminum alloy. CaSi2 can not heat treatment of aluminum alloy. Trace calcium is beneficial to the removal of hydrogen in the aluminum liquid.
Lead, tin, bismuth element is a low melting point metal, they in aluminum solid solubility small, slightly lower strength of the alloy, but can improve the cutting performance. The addition of bismuth in high magnesium alloy can prevent sodium embitterment.
Antimony is mainly used as a modifier in the cast aluminum alloy, deformation of aluminum alloy is rarely used. Sodium embitterment is only used in the aluminum alloy of Al-Mg deformation.
The structure can improve the beryllium oxide film on the deformation in aluminum alloy; reduce the loss and inclusion casting. Beryllium is a toxic element, can make people produce allergic poisoning. Therefore, contact with food and beverage aluminum alloy can not contain beryllium. The content of beryllium in welding materials is usually controlled at 8 g/ml. Aluminum alloy used as welding matrix should also be controlled by the content of beryllium.
Sodium in aluminum hardly dissolved, the maximum solid solubility less than 0.0025%, the melting point of sodium low (97.8 DEG C), alloy in the presence of sodium, in the solidification process of adsorption in the dendrite surface or grain boundary and thermal processing, grain boundaries of the sodium form liquid adsorption layer, brittle fracture, forming nails compounds, free in the presence of sodium, the sodium embitterment ". When the content of magnesium is over 2%, the magnesium is in the silicon, and the free sodium is released ". Because of the high magnesium alloy does not allow the use of sodium flux. Prevent chlorination method of sodium brittleness and the sodium form NaCl is discharged into a slag and bismuth addition to produce Na2Bi into metal matrix; and antimony generation Na3Sb or adding rare earth can also play the same role.
