Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C18/00—Alloys based on zinc
  • C22C18/04—Alloys based on zinc with aluminium as the next major constituent

Definitions

• the present invention relates to zinc-based alloys with improved ductility.
• a zinc alloy intended for gravity casting is known in particular having a breaking load of the order of 400 MPa. This value was reached by assuring the alloy an aluminum content of about 27%, with additions of copper and magnesium. The ductility of this alloy is however poor, because its elongation is, under the best casting conditions, between 4 and 8%. The same is true of other known alloys, containing approximately 35% of aluminum and additions, in particular of copper.
• the present invention relates to a zinc-based alloy, intended for gravity casting and having improved ductility properties.
• the elongation is clearly improved, while the breaking load remains at least equal to that of the alloys containing 27% or 35% of aluminum.
• a zinc alloy, object of the present invention containing 25% to 40% of aluminum, 0.5% to 5% of copper and up to 0.1% of magnesium, has a content of boron between 5 ppm and 0.1%, and preferably between 0.005% and 0.050%.
• a first particular modality consists in adding to the alloy of titanium in a content of between 25 ppm and 0.5%, and preferably between 0.005% and 0.050%.
• an alloy in accordance with the invention contains, in addition to boron, zirconium and / or strontium in a content of less than 0.1%.
• a zinc alloy which is the subject of the present invention containing 25% to 40% of aluminum, 0.5% to 5% of copper and up to 0.1% of magnesium, has a total content of rare earths, preferably lanthanum and cerium, between 5 ppm and 0.1%, and preferably between 0.005% and 0.050%.
• rare earths can also be in the form of the mixture called mischmetall which contains either about 60% - 90% La, 6% - 10% Ce, the balance being made up of other earths rare and other residual elements (Fe, Mg, Al, Si), i.e. 45% - 60% Ce, the balance being made up of other rare earths or other residual elements (Fe, Mg, Al, Si).
• the table below illustrates the effect of the additions, in accordance with the invention, which have just been described, on the breaking load and on the elongation of a zinc-based alloy containing 27% aluminum, 1% copper and 0.02% magnesium.
• Alloy A is the previously known alloy; it has a low ductility, expressed by an elongation of between 4% and 8%.
• the Blet B 2 alloys in accordance with the first variant of the invention show that an addition of boron within the limits indicated makes it possible to very significantly increase the value of the elongation, and consequently to improve the ductility without altering the load. alloy breakage.
• the alloys C1 and C2 meeting the first particular modality of this first variant also exhibit increased elongation; in addition, the breaking load is slightly increased in the case of the alloy C 1 , whose boron and titanium contents respect the preferential ratio of 1: 5.
• the alloy C 3 has a breaking load markedly improved, but the elongation remained at that of the reference alloy, despite the presence of boron. This behavior seems to be explained by the formation of intermetallic compounds of boron and titanium, which counteract the beneficial effect of boron on elongation, when the titanium contents are high.
• Alloy D I which corresponds to the second particular modality of the first variant, has a significantly higher breaking load than the basic alloy, associated with elongations which are also improved.
• the alloys E 1 and E 2 in accordance with the second variant of the invention, show that an addition of lanthanum or cerium within the limits indicated, makes it possible to raise very significantly significantly the value of the elongation, and consequently of improving the ductility, without altering the breaking load of the alloy.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Conductive Materials (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Electrolytic Production Of Metals (AREA)

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Applications Claiming Priority (6)

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• 1984
  • 1984-01-20 DE DE8484870009T patent/DE3477206D1/de not_active Expired
  • 1984-01-20 EP EP84870009A patent/EP0119180B1/de not_active Expired
  • 1984-02-08 WO PCT/BE1984/000003 patent/WO1993013230A1/fr not_active Ceased

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