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US20070212250A1 - Die cast magnesium alloy - Google Patents

Die cast magnesium alloy Download PDF

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Publication number
US20070212250A1
US20070212250A1 US11/571,038 US57103805A US2007212250A1 US 20070212250 A1 US20070212250 A1 US 20070212250A1 US 57103805 A US57103805 A US 57103805A US 2007212250 A1 US2007212250 A1 US 2007212250A1
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US
United States
Prior art keywords
zinc
alloy
magnesium
calcium
alloys
Prior art date
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Abandoned
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US11/571,038
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English (en)
Inventor
Trevor Abbott
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cast Centre Pty Ltd
Original Assignee
Cast Centre Pty Ltd
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Filing date
Publication date
Priority claimed from AU2004903446A external-priority patent/AU2004903446A0/en
Application filed by Cast Centre Pty Ltd filed Critical Cast Centre Pty Ltd
Assigned to CAST CENTRE PTY LTD, reassignment CAST CENTRE PTY LTD, ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ABBOTT, TREVOR BRUCE
Publication of US20070212250A1 publication Critical patent/US20070212250A1/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C23/00—Alloys based on magnesium
    • C22C23/04—Alloys based on magnesium with zinc or cadmium as the next major constituent

Definitions

  • the present invention relates to magnesium/zinc/aluminium (Mg—Zn—Al) alloys which contain small amounts of calcium and/or beryllium.
  • magnesium alloys Due to their excellent strength to weight ratios, magnesium alloys are well recognised as commercially desirable materials.
  • the most commonly used magnesium alloy is AZ91 which contains about 90% magnesium, 9% aluminium and 1% zinc.
  • zinc is about 65% of the price of magnesium and hence magnesium alloys of increased zinc content would be desirable provided that they exhibited commercially satisfactory properties.
  • magnesium alloys which are sufficiently resistant to oxidation to obviate the need for protective cover gases or the like when molten alloy is exposed to air would be advantageous.
  • “Its general object is the provision of improvements which mitigate difficulties arising from the propensity of magnesium to oxidise when in contact with air, moisture or with other media containing oxygen.
  • Commercial usefulness of a metal, such as magnesium depends not alone upon its essential properties, or those which may be imparted to it by alloying it with lesser quantities of other metals, but also upon the ease with which the metal, or such alloys, may be remelted, cast, worked or otherwise formed into the various conditions and shapes necessary to ultimate use.
  • the propensity of magnesium to destructively oxidise when in the molten state is great. Under many conditions, normal to the handling of other molten metals, molten magnesium burns or otherwise reverts to the oxide in very substantial part.
  • magnesium base alloys When in the solid state, magnesium base alloys oxidise, under some conditions, to a comparatively severe extent. Since extensive handling of magnesium and magnesium base alloys in the molten condition is a necessary preliminary to operations designed to shape or work the metal, the difficulties presented by this pronounced tendency to oxidise are encountered in almost every instance and are universal in the magnesium industry.”
  • U.S. Pat. No. 4,543,234 (Foerster) relates to Mg—Al—Zn—Si—Mn alloys containing 0.0025-0.0125% dissolved beryllium “to inhibit burning, with the amount of beryllium being increased with increasing oxygen content of the atmosphere.”
  • U.S. Pat. No. 4,543,234 also notes that “a beryllium content of on the order of 0.001 percent is considered to be inadequate for the purpose of inhibiting excessive oxidation of the molten magnesium.”
  • U.S. Pat. No. 5,855,697 (Luo et al) relates to a magnesium alloy having superior elevated temperature properties and is not concerned with oxidation suppression.
  • U.S. Pat. No. 5,855,697 notes that calcium addition is known to improve the high-temperature strength and creep resistance and that calcium contents of 0.2% by weight and greater are desirable. It is further noted that such calcium additions severely deteriorate castability rendering the alloy incapable of being cast by conventional die casting processes.
  • U.S. Pat. No. 5,855,697 teaches that the castability of a magnesium-aluminium-calcium alloy can be restored by inclusion of zinc.
  • the presence of zinc is said to enable calcium to “be added in amounts up to 2 weight %, preferably up to 1.5 weight %, in order for the alloy to achieve the maximum creep resistance while maintaining good die-castability.”
  • the present invention provides an alloy consisting of:
  • A is 10% Zn-2.5% Al,
  • B is 10% Zn-5% Al
  • D is 19% Zn-2.5% Al
  • E is 0.01% Ca-0% Be
  • F is 1% Ca-0% Be
  • G is 0% Ca-0.0025% Be
  • H is 0% Ca-0.0001% Be optionally Mn
  • FIG. 1 The quadrangle defined by lines AB, BC, CD, and DA is illustrated in FIG. 1 which is a plot of aluminium v zinc content.
  • FIG. 2 The quadrangle defined by lines EF, FG, GH and HE is illustrated in FIG. 2 which is a plot of beryllium v calcium content.
  • All alloys of the present invention contain a minimum of 10% zinc, preferably greater than 11% zinc, more preferably greater than 12% zinc, more preferably about 12-14% zinc, and most preferably about 12-13% zinc.
  • the present inventor has ascertained that such zinc additions suppress the ignition of the alloy in the molten state in the absence of alkaline earth elements such as beryllium or calcium. Without wishing to be bound by theory, the ignition suppression is believed to be a consequence of the vapour pressures of magnesium and zinc and the amount of zinc present in the alloys.
  • vapour pressures of zinc and magnesium above a molten alloy can be calculated using information from a paper entitled “Vapour Composition and Activities in Mg—Zn Liquid Alloy at 923K” by K. T. Jacob, S. Srikanth and Y. Waseda in Thermochimica Acta, 1988, vol 130, pages 193-203.
  • the ratio of the vapour pressure of zinc relative to the vapour pressure of magnesium increases rapidly as the amount of zinc in the molten alloy is increased.
  • a molten alloy containing 10% by weight of zinc and 90% by weight of magnesium is calculated to produce a vapour containing 22% by weight of zinc and 78% by weight of magnesium.
  • the zinc vapour is believed to interfere with ignition of the magnesium vapour.
  • molten alloys containing more than 10% zinc resist ignition they tend to form a blackened layer on the surface of a solidified sample.
  • the addition of a small amount of calcium and/or a small amount of beryllium has been found sufficient to result in a shiny surface appearance when solidified.
  • As little as 0.01% calcium or as little as 0.0001% beryllium have been found sufficient in combination with zinc and aluminium contents in accordance with the present invention to produce this effect.
  • the shiny surface appearance is believed to be a consequence of an enrichment in the calcium and/or beryllium content of the oxide layer formed on the surface of the melt.
  • the calcium content is preferably 0.01-0.5%, more preferably 0.01-0.3%, more preferably 0.02-0.3%, more preferably 0.05-0.3%, more preferably 0.05-0.2%, more preferably 0.05-0.15%, most preferably about 0.1%. Calcium contents in excess of 1% are undesirable because they have been found to diminish the mechanical properties of the alloys and cause die soldering when die cast.
  • the beryllium content is preferably 0.0002-0.0025%, more preferably 0.0002-0.002%, more preferably 0.0005-0.002%, more preferably 0.0005-0.0015%, more preferably 0.0005-0.001%, most preferably about 0.0008%.
  • Beryllium contents in excess of 0.0025% are unnecessary in order to obtain the desired effect. In view of beryllium's toxicity it is therefore desirable to minimise its use by keeping the beryllium content below this level.
  • Manganese (Mn) is an optional component of the alloys which may be included if there is a requirement for iron (Fe) removal.
  • Mn is a component it is preferably present in amounts less than 1%, more preferably less than 0.75%, more preferably 0.1-0.5%, more preferably 0.2-0.4% and most preferably about 0.3%.
  • Other elements may also form optional components of the alloys provided that they do not adversely affect commercially significant properties of the alloys.
  • alloys of the present invention contain less than 100 ppm iron, more preferably less than 40 ppm iron, and most preferably substantially no iron.
  • All alloys of the present invention contain a minimum of 2.5% aluminium.
  • alloys of the present invention contain 2.5-5% aluminium, more preferably about 3-4.5% aluminium, and most preferably about 3.5-4% aluminium.
  • the present inventor has also ascertained that brittleness increases to the aluminium rich and zinc rich side of line CD.
  • alloys of the present invention contain less than 25 ppm nickel, more preferably less than 10 ppm nickel, and most preferably substantially no nickel.
  • alloys of the present invention contain less than 0.1% silicon, more preferably less than 0.08% silicon, and most preferably substantially no silicon.
  • various preferred embodiments of the present invention exhibit one or more other commercially desirable properties such as recyclability, castability, resistance to hot cracking, corrosion resistance, creep resistance, low sound dampening coefficients and good surface finish.
  • a significant commercial impediment to the use of magnesium alloys is the waste which results from the difficulty of recycling so-called “returns” which include runners, biscuits etc from die casting.
  • returns which include runners, biscuits etc from die casting.
  • 30-70% of a diecasting consists of runners and biscuits that need to be recycled.
  • Difficulties in the recycling of magnesium alloys are generally attributed to a significant amount of surface oxides which result in high melt losses in the form of dross and sludge.
  • recycling is carried out in a separate operation in order to enable removal of oxides without entraining them in the melt and including them in subsequent diecastings.
  • the present inventor has ascertained that at least preferred embodiments of the alloys of the present invention have enhanced recyclability.
  • Behaviour1 the surface of the casting initially turned black then ignited as illustrated in FIG. 3 .
  • Behaviour2 the surface turned black but did not ignite as illustrated in FIG. 4 .
  • Behaviour3 the surface was initially shiny then later ignited as illustrated in FIG. 5 .
  • Behaviour4 the surface remained shiny with no ignition as illustrated in FIG. 6 .
  • Table 1 lists the behaviour observed for a range of different alloys.
  • the addition of more than 10% of zinc was sufficient to prevent burning and resulted in a blackened surface.
  • Calcium additions without zinc produced a shiny surface, but 0.8% calcium was required to prevent ignition.
  • the addition of calcium to alloys with sufficient zinc to prevent burning converted the surface to a shiny appearance with as little as 0.05% calcium producing a partially shiny surface.
  • Increases in the calcium content lead to a progressive decrease in the amount of blackening. At 0.4% calcium no blackening was observed.
  • the alloys containing 10% zinc turned black then ignited, while alloys with higher zinc contents did not ignite.
  • the alloys were deliberately poured at high temperature (700° C.) to remove low temperature as a possible reason for absence of ignition. It is anticipated that commercial casting would occur at a temperature in the order of 30-40° C. lower with a consequent decrease in the propensity for ignition.
  • FIG. 7 illustrates the behaviour of pure magnesium which oxidized so rapidly that it was not possible to expose shiny metal.
  • FIG. 8 illustrates the behaviour of a Mg-5% Zn alloy which also oxidized rapidly. Shiny metal could be exposed, but only for a small fraction of a second.
  • FIG. 9 illustrates the behaviour of a Mg-10% Zn alloy. The oxidation tendency was greatly reduced as indicated by the absence of “cauliflower-like” growths around the perimeter and the increase in shiny metal exposed.
  • FIGS. 10 and 11 illustrate the behaviour of Mg-15% Zn and Mg-20% Zn alloys respectively. In both cases it was relatively easy to expose shiny metal which took several seconds to re-oxidize. Neither formed “cauliflower-like” growths.
  • FIGS. 12, 13 and 14 show the appearance of the alloys immediately after pouring ( FIGS. 12 a , 13 a and 14 a ) then a short time (about 1 minute) later ( FIGS. 12 b , 13 b and 14 b ).
  • FIGS. 12 a and 12 b show the behaviour of a zinc free alloy. After initially appearing shiny this alloy developed “cauliflower-like” growths then later ignited.
  • FIGS. 13 a and 13 b show the behaviour of an alloy containing 5% zinc. This alloy also developed “cauliflower-like” growths and ignited, but at a slower rate than the zinc free alloy of FIG. 12 .
  • FIGS. 14 a and 14 b show the behaviour of a 10% zinc alloy. In this alloy both the “cauliflower-like” growths and ignition were suppressed. The ultimate appearance after the sample was allowed to air cool to room temperature was unchanged from FIG. 14 b.
  • melts were prepared and poured into a mould in the same manner as described above in Example 1.
  • the melts contained 13% zinc, 3.6% aluminium and varying amounts of beryllium and calcium.
  • the calcium and beryllium contents of these alloys are given in Table 2.
  • Alloys 1 and 6 were calcium-free and alloys 1-4 were beryllium-free.
  • the final appearance of the castings is shown in FIG. 15 . All of the alloys that contained some calcium or beryllium solidified with a shiny skin. Alloy 1 which was free of both calcium and beryllium solidified with a blackened skin.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Prevention Of Electric Corrosion (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Materials For Medical Uses (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Dental Preparations (AREA)
  • Forging (AREA)
US11/571,038 2004-06-24 2005-06-23 Die cast magnesium alloy Abandoned US20070212250A1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
AU2004903446A AU2004903446A0 (en) 2004-06-24 Die cast magnesium alloy
AU2004903446 2004-06-24
AU2004906768A AU2004906768A0 (en) 2004-11-25 Die cast magnesium alloy
AU2004906768 2004-11-25
PCT/AU2005/000903 WO2006000022A1 (fr) 2004-06-24 2005-06-23 Alliage de magnesium moule

Publications (1)

Publication Number Publication Date
US20070212250A1 true US20070212250A1 (en) 2007-09-13

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US11/571,038 Abandoned US20070212250A1 (en) 2004-06-24 2005-06-23 Die cast magnesium alloy

Country Status (12)

Country Link
US (1) US20070212250A1 (fr)
EP (1) EP1761652A4 (fr)
JP (1) JP4729567B2 (fr)
KR (1) KR20070049114A (fr)
CN (1) CN101006191B (fr)
CA (1) CA2572002A1 (fr)
IL (1) IL180193A0 (fr)
MX (1) MXPA06015208A (fr)
NO (1) NO20070414L (fr)
RU (1) RU2007101661A (fr)
TW (1) TW200600588A (fr)
WO (1) WO2006000022A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2506337C1 (ru) * 2012-11-13 2014-02-10 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Национальный исследовательский технологический университет "МИСиС" Литейный магниевый сплав
CN105132769A (zh) * 2015-09-11 2015-12-09 湖南大学 一种低铝低钙、高Ca/Al比Mg-Ca-Al合金及制备方法

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2361946C1 (ru) * 2008-02-28 2009-07-20 Юлия Алексеевна Щепочкина Сплав на основе магния
EP2295613B1 (fr) * 2008-06-03 2015-01-14 National Institute for Materials Science ALLIAGE À BASE DE Mg
CN102108466B (zh) * 2009-12-23 2012-07-11 中国科学院金属研究所 耐蚀的镁合金
CN102965556B (zh) * 2012-11-20 2014-12-31 南通大学 多元Mg-Zn-Al基镁合金及其制备方法
CN104264022B (zh) * 2014-10-01 2016-08-10 无棣向上机械设计服务有限公司 一种镁合金及其制备方法
CN105401032B (zh) * 2015-12-14 2017-08-25 宝山钢铁股份有限公司 一种低成本高导热压铸镁合金及其制造方法
CN105937005B (zh) * 2016-06-17 2019-12-06 东北大学秦皇岛分校 均匀分布粒状准晶和棒状相的时效强化镁合金及制备方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2380200A (en) * 1942-07-10 1945-07-10 Aluminum Co Of America Magnesium base alloy
US4659377A (en) * 1979-05-23 1987-04-21 Nl Industries, Inc. Method for producing an oxidation resistant magnesium alloy melt
US5855697A (en) * 1997-05-21 1999-01-05 Imra America, Inc. Magnesium alloy having superior elevated-temperature properties and die castability

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3892565A (en) * 1973-10-01 1975-07-01 Nl Industries Inc Magnesium alloy for die casting
JPH06306523A (ja) * 1993-04-20 1994-11-01 Ube Ind Ltd 耐熱マグネシウム合金
JPH0881728A (ja) * 1994-07-12 1996-03-26 Ube Ind Ltd 耐クリープ性、耐食性を有するマグネシウム合金
JP2001247926A (ja) * 2000-03-03 2001-09-14 Japan Steel Works Ltd:The 流動性に優れたマグネシウム合金およびマグネシウム合金材
JP2002266044A (ja) * 2001-03-09 2002-09-18 Aisin Takaoka Ltd マグネシウム合金
RU2220221C2 (ru) * 2002-02-20 2003-12-27 Открытое акционерное общество "АВИСМА титано-магниевый комбинат" Сплав на основе магния

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2380200A (en) * 1942-07-10 1945-07-10 Aluminum Co Of America Magnesium base alloy
US4659377A (en) * 1979-05-23 1987-04-21 Nl Industries, Inc. Method for producing an oxidation resistant magnesium alloy melt
US5855697A (en) * 1997-05-21 1999-01-05 Imra America, Inc. Magnesium alloy having superior elevated-temperature properties and die castability

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2506337C1 (ru) * 2012-11-13 2014-02-10 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Национальный исследовательский технологический университет "МИСиС" Литейный магниевый сплав
CN105132769A (zh) * 2015-09-11 2015-12-09 湖南大学 一种低铝低钙、高Ca/Al比Mg-Ca-Al合金及制备方法

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Publication number Publication date
JP2008503651A (ja) 2008-02-07
IL180193A0 (en) 2007-06-03
EP1761652A4 (fr) 2009-02-18
CN101006191A (zh) 2007-07-25
RU2007101661A (ru) 2008-07-27
CA2572002A1 (fr) 2006-01-05
MXPA06015208A (es) 2007-03-15
WO2006000022A1 (fr) 2006-01-05
CN101006191B (zh) 2010-11-24
TW200600588A (en) 2006-01-01
NO20070414L (no) 2007-03-20
EP1761652A1 (fr) 2007-03-14
JP4729567B2 (ja) 2011-07-20
KR20070049114A (ko) 2007-05-10

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Owner name: CAST CENTRE PTY LTD,, AUSTRALIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ABBOTT, TREVOR BRUCE;REEL/FRAME:018792/0063

Effective date: 20070116

STCB Information on status: application discontinuation

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