Rare Earth Alloy Of Copper And Copper-nickel Alloy In The Role Of Law And Applied Research

This research is supported by achievement transformation items of Jiangsu province for science and technology-"Research and Industrialization of RE-Cu Alloys and Interrelated Technologies" [BA2006034]. For the purpose of broadening applications of RE elements on the industrial fabrication of copper and copper alloys, a series basic research on some applied sections of RE on copper and copper alloys industry is carried out. The primary investigations of this paper include three main parts: effects of RE elements on microstructures and mechanical properties of pure copper, the development of Cu-RE interalloys and its' application on scrap copper, influences of RE elements on flushing corrosion-resistance of marine water for BFe10-1-1 alloy. The main conclusions are as follows:1. Study on the effects of RE elements on microstructures and mechanical properties of pure copperThe effects of RE elements on microstructures and mechanical properties of pure copper are investigated from the point of view of addition and content of RE:(1) RE effectively purifies the molten copper and deprives harmful elements from pure copper. But the absorptivity of RE in copper is very low when just adding RE to molten bath directly.(2) The proper RE additions can refine the microstructure and optimize the mechanical properties of pure copper. Over-added RE declined to form a mass of RE-rich phases deteriorating the mechanical properties.(3) The recrystallization temperature of pure copper rises with increasing of RE content.2. The development of Cu-RE interalloys and its' application on scrap copperFor the sake of reducing the burning loss of RE and simplifying the casting craft, three kinds of Cu-RE binary interalloy refiners were fabricated. Scrap coppers were refined respectively by Cu-RE refiners. The refinement of Cu-RE refiners on scrap coppers was investigated using various research methods:(1) Three kinds of Cu-RE binary interalloys were fabricated according to eutectic composition Cu-15%RE: Cu-14.6%La, Cu-6.8%Ce-4.2%La and Cu-9.6%Ce-2.0%La. Thereinto, Cu-RE interalloy Cu-14.6%La is eutectic structure; both Cu-6.8%Ce-4.2%La and Cu-9.6%Ce-2.0%La are hypoeutectic structure. The majority phases in Cu-RE interalloys are: Cu,LaCu₆,CeOi₆,Ca₄La₆ Cu₁₃La;(2) Contrasting to other two refiners, the refinement of Cu-RE refiner Cu-14.6%La is the best. Refiners deprive harmful elements from matrix effectively such as: O,S,P,Bi,Pb,Fe,Al, and purify the molten bath. In addition, Cu-RE refiner can refine grains, purify grain boundaries and improve the structures;(3) Comparing to adding RE directly, adding Cu-RE interalloy to molten bath can reduce burning loss of RE greatly, simplify the casting craft and accurately control the content of RE.3. Study on the influences of RE elements on flushing corrosion-resistance of BFe10-1-1 alloys in marine waterThe real environments of marine water flushing corrosion were simulated in laboratory and the contrast tests of marine water flushing corrosion about BFe10-1-1 alloys with different RE content were carried out also. The results are following:(1) For the same chemical compositions, the faster the water flows, the higher the corrosion velocity of BFe10-1-1 alloy is. Fixing the velocity of flow, BFe10-1-1 alloy has the best flushing corrosion-resistance of marine water when the RE content is 0.014wt%.(2) When BFe10-1-1 alloy has proper RE elements, its corrosive surface form a layer of compact corrosive products which contant RE phases such as CeNi₅. The corrosive products combine with each other firmly and difficult to fall off from surface under the flushing of marine water.