Composite modifier and modification method for cast aluminum alloy with iron-rich phase modification

Abstract

The invention discloses a composite alterant of a cast aluminum alloy for iron-enriched phase alteration and an alteration method thereof, and relates to the field of composite alteration of the castaluminum alloy. The composite alterant comprises an Mn agent, an Al-RE intermediate alloy and an Al-Sr intermediate alloy, wherein the Mn agent is an Al-Mn intermediate alloy or a Mn additive; the adding ratio of the Mn agent is 30-90% of the Fe content in the cast aluminum alloy; the RE adding amount of the Al-RE intermediate alloy is 0.05-0.2% of the melt mass of the cast aluminum alloy; and theSr adding amount of the Al-Sr intermediate alloy is 0.02-0.05% of the melt mass. The composite alterant is specifically suitable for a high-strength and high-toughness cast aluminum silicon alloy with low Fe content and a die-cast aluminum silicon alloy with high iron content, and can achieve synchronous refining of three structures of alpha-Al, eutectic silicon and an iron-enriched phase to improve the alloy ductility.

Description

Technical field [0001] The present invention relates to the technical field of cast aluminum alloy modification technology, and in particular to a composite modifier of cast aluminum alloy with iron-rich phase modification and a modification method thereof. Background technique [0002] Al-Si series cast aluminum alloy has the advantages of good casting performance, low shrinkage rate and thermal expansion coefficient, good weldability and corrosion resistance, etc., and is widely used in automobiles and motorcycles, aerospace, communications, electronic appliances and other fields. Fe is one of the most common impurity elements in cast aluminum alloys, and its content gradually increases as the number of aluminum alloy cycles increases. Due to the low solubility of Fe in aluminum alloys, the iron-rich phase formed has the characteristics of high hardness and high brittleness. It is prone to internal cracking when subjected to stress and becomes a source of cracks, which greatly ...

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Problems solved by technology

Song Dongfu【Song Dongfu, Zhou Nan, Xu Jing, et al. Effect of composite addition of Mn and B on iron-rich phase characteristics of aluminum-silicon alloy[J]. Rare Metal Materials and Engineering, 2016,45(8):2133-2138.】passed Adding Mn and B to iron-containing aluminum-silicon cast aluminum alloys can obtain fine and evenly distributed dendritic iron-rich phases, and at the same time promote the transformation of α-Al grains from dendrites to equiaxed crystals, iron-rich phases and α- The refinement and modification effect of Al is very significant, but it has no obvious effect on the refinement of eutectic silicon phase

Birol【Birol Y.Grain refinement and modification of Al–Si foundry alloys with B and Sr additions[J].MaterialsScience&Technology,2014,30(10):1154-1161.】confirmed that the compound addition of Sr and B in an appropriate amount can simultaneously achieve α -Refinement and modification of Al grains and eutectic silicon, but no modification of iron-rich phases involved

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