A high-strength and high-toughness non-heat-treatable die-casting aluminum-silicon alloy and a preparation method therefor are provided. The alloy includes the following components in percentage by weight: 8.0-10.0% of Si, 0.1-0.5% of Mg, 0.5-0.8% of Mn, 0.05-0.5% of Cu, 0.05-0.2% of Ti, 0.01-0.05% of Sr, 0.01-0.1% of V, 0.01-0.15% of RE, less than 0.2% of Fe, less than or equal to 0.4% of other impurities and the balance of Al. Based on modification refinement of eutectic Si by Sr, during preparation, the elements V and RE are imported to further significantly refine eutectic Si structures, so that the alloy obtains features of high strength and high toughness with a high Si content. Under a die-casting condition, the yield strength of the alloy can be 120-160 Mpa, the tensile strength thereof can be 260-320 Mpa and the ductility thereof can be 10-15%.

A method of purifying yttrium involves purifying element yttrium by high-temperature saturated dissolution, low-temperature recrystallization, high-temperature reduction and vaporization-based removal of impurities, in a simple manner, and at a low cost, such that yttrium element is unlikely to be contaminated by any raw material used in a manufacturing process.

A method of decarburizing a molten alloy may generally comprise injecting a first gas comprising at least one of argon, carbon dioxide, and oxygen through a first fluid-conducting portion of a tuyere into the molten alloy below the surface of the molten alloy, and injecting a second gas comprising at least one of argon and carbon dioxide through a second fluid-conducting portion of the tuyere into the molten alloy below the surface of the molten alloy. The tuyere may comprise an inner portion concentrically aligned within an outer portion to define an annulus therebetween. The first gas may be injected through the inner portion, and the second gas may be injected through the annulus.

A method of decarburizing a molten alloy may generally comprise injecting a first gas comprising at least one of argon, carbon dioxide, and oxygen through a first fluid-conducting portion of a tuyere into the molten alloy below the surface of the molten alloy, and injecting a second gas comprising at least one of argon and carbon dioxide through a second fluid-conducting portion of the tuyere into the molten alloy below the surface of the molten alloy. The tuyere may comprise an inner portion concentrically aligned within an outer portion to define an annulus therebetween. The first gas may be injected through the inner portion, and the second gas may be injected through the annulus.

Methods for degassing and for removing impurities from molten metals are disclosed. These methods can include operating an ultrasonic device in a molten metal bath, and adding a purging gas into the molten metal bath in close proximity to the ultrasonic device.

Methods for degassing and for removing impurities from molten metals are disclosed. These methods can include operating an ultrasonic device in a molten metal bath, and adding a purging gas into the molten metal bath in close proximity to the ultrasonic device.

A heat-treatment-free die-cast aluminum alloy includes: 10.0 to 12.0 wt % of Si, 0.9 to 1.5 wt % of Mg 2.5 to 3.5 wt % of Cu, 0.4 to 0.8 wt % of Mn, 0.9 to 1.5 wt % of Zn, 0.1 to 0.2 wt % of Ti, 0.03 to 0.06 wt % of Sr, 0.18 wt % or less of Fe, 0.15 wt % or less of a rare earth element including at least one of Sm or Y, 0.1 wt % or less of an impurity element, and a balance of Al, based on a total weight of the die-cast aluminum alloy.

A heat-treatment-free die-cast aluminum alloy includes: 10.0 to 12.0 wt % of Si, 0.9 to 1.5 wt % of Mg 2.5 to 3.5 wt % of Cu, 0.4 to 0.8 wt % of Mn, 0.9 to 1.5 wt % of Zn, 0.1 to 0.2 wt % of Ti, 0.03 to 0.06 wt % of Sr, 0.18 wt % or less of Fe, 0.15 wt % or less of a rare earth element including at least one of Sm or Y, 0.1 wt % or less of an impurity element, and a balance of Al, based on a total weight of the die-cast aluminum alloy.

A furnace has a melting chamber with a periphery defined by a surrounding wall structure. The furnace is provided with a purge system configured to direct inert gas to flow downward in the melting chamber in the configuration of a curtain that adjoins the wall structure and reaches only partially around the periphery of the melting chamber.

A furnace has a melting chamber with a periphery defined by a surrounding wall structure. The furnace is provided with a purge system configured to direct inert gas to flow downward in the melting chamber in the configuration of a curtain that adjoins the wall structure and reaches only partially around the periphery of the melting chamber.