Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C25/00—Alloys based on beryllium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium

Definitions

• the present invention relates to a Be-Al-based alloy which can be suitably used for an actuator of a hard disk device.
• Be-Al-based alloy is considered to be a prominent material in view of light weight and high strength or high Young's modulus properties.
• Be-Al-based alloy For manufacturing products from Be-Al-based alloy, it is customary to prepare ingot by vacuum casting and perform subsequent process steps such as extrusion, rolling, drawing, forging, and the like.
• Be-Al-based alloy has a composite structure in which beryllium-rich phase and aluminum-rich phase coexist.
• Be-Al-based alloy When Be-Al-based alloy is subjected to extrusion process after vacuum casting, since the flowability of the material is poor, there have been noted problems that high extrusion pressure is needed, and that die abrasion is notable and lifetime is shortened. Further, when Be-Al-based alloy is formed into ingot by vacuum casting process, beryllia (BeO) porcelain is required for a crucible material, which is difficult to produce and is thus expensive.
• BeO beryllia
• alumina porcelain may be dissolved by the strong reductivity of Be according to the following reaction formula: Al 2 O 3 + 3Be(Liq) ⁇ 2Al(Liq) + 3BeO, with the result that the crucible may be eroded.
• a Be-Al-based alloy having an excellent flowability comprising 30 to 95 wt% Be, not more than 1.0 wt% Mg, and the balance which consists essentially of Al.
• the Be-Al-based alloy according to the invention may further comprise at least one member selected from the group consisting of Si: 0.5 to 5.0 wt%, Ag: 0.2 to 5.0 wt% and Zr: 0.2 to 5.0 wt%, as an Al-rich phase strengthening element.
• the Be-Al-based alloy according to the invention may further comprise at least one member selected from the group consisting of Co: 0.05 to 5.0 wt%, Ni: 0.05 to 5.0 wt% and Cu: 0.2 to 5.0 wt%, as a Be-rich phase strengthening element.
• the Be-Al-based alloy according to the invention may further comprise at least one member selected from the group consisting of Sr: 0.005 to 0.3 wt% and Sb: 0.005 to 0.3 wt%, as an extensibility improving element.
• Be is an element useful for improving the strength and hardness by forming eutectic structure with Al.
• the Be content is less than 30 wt%, the desired improvement of strength and hardness cannot be sufficiently achieved.
• the Be content exceeds 95 wt%, the formability is notably deteriorated. Therefore, according to the invention, Be is contained within the ranges of 30 to 95 wt%.
• Mg is an important element for remarkably improving the flowability of Be-Al-based alloy.
• Young's modulus of the alloy is notably decreased. Therefore, according to the invention, the Mg content is limited to be not more than 1.0 wt%.
• Mg contents is preferably not less than 0.05 wt% in order to obtain good flowability and adequately decrease the extrusion pressure during the extrusion stage.
• Si 0.5 to 5.0 wt %
• Ag 0.2 to 5.0 wt%
• Zr 0.2 to 5.0 wt%
• Si, Ag and Zr effectively contribute to strengthen an Al-rich phase of the alloy.
• these contents of these elements content are too small, the desired strengthening effect is difficult to achieve.
• the contents of these elements are excessive, the density of the alloy becomes higher so that the essentially required properties of Be-Al-based alloy, such as the desired lightness, cannot be readily achieved. Therefore, these elements are contained by the above-mentioned respective ranges.
• Co 0.005 to 5.0 wt%.
• Ni 0.05 to 5.0 wt%.
• Cu 0.05 to 5.0 wt%
• Co, Ni and Cu also effectively contribute to strengthen a Be-rich phase of the alloy.
• the desired strengthening effect is difficult to achieve.
• the density of the alloy becomes higher so that the essentially required properties of Be-Al-based alloy, such as the desired lightness, cannot be readily achieved. Therefore, these elements are contained by the above-mentioned respective ranges.
• Sr and Sb are respectively useful elements for improving the extensibility of the alloy.
• the contents of these element are less than 0.005 wt%, the desired improvement cannot be sufficiently achieved.
• the contents of these elements exceed 0.3 wt%, the cost of the alloy increases though the extensibility cannot be further improved anymore.
• Mg in the range of not less than 1.0 wt% is added into the Be-Al-based alloy, so as to remarkably improve the flowability of the Be-Al-based alloy.
• the extrusion pressure during the extrusion stage can be remarkably decreased when products are manufactured.
• MgO magnesia
• the crucible is essentially free from erosion.
• Be-Al-based ingots (size: 70 mm ⁇ ⁇ 250 mm) having compositions as shown in Table 1 were extruded from an extrusion die under the temperature condition of 490°C and the extrusion ratio of 10. The extrusion pressure, Young's modulus of the products and the dies lifetime are also shown in Table 1.
• the asterisks (*) in Table 1 indicate alloys which were made by magnesia (MgO) crucible in melting, and Mg was added from such crucible to the alloy.
• No. composition (wt%) Young's Modulus (kgf/mm 2 ) extrusion pressure (kgf/cm 2 ) lifetime of the die note Be Al Mg 1 65.0 34.5 0.5 19000 4200 1.2 inventive example 2 65.0 34.0 1.0 18950 4050 1.3 inventive example 3 45.0 54.9 0.1 15850 2400 1.1 inventive example 4 45.0 54.5 0.5 15800 2340 1.2 inventive example 5 45.0 54.0 1.0 15750 2300 1.2 inventive example 6 60.0 35.0 5.0 18500 3950 1.3 comparative example 7 63.0 35.0 2.0 18550 4000 1.2 comparative example 8 45.0 45.0 10.0 14400 2100 1.3 comparative example 9 45.0 50.0 5.0 15100 2150 1.3 comparative example 10 45.0 53.0 2.0 15200 2250 1.2 comparative example 11 65.0 35.0
• the Be-Al-based alloys containing a proper amount of Mg according to the present invention serve to effectively decrease the extrusion pressure without essentially decreasing Young's modulus. It can be also clearly seen that the addition of Mg contributes to extend the lifetime of the dies.
• composition (wt%) Young's Modulus (kgf/mm 2 ) extrusion pressure (kgf/cm 2 ) lifetime of the die note Be A1 Mg others 1 65.0 34.0 0.5 Co: 0.5 19050 4250 1.2 inventive example 2 65.0 32.0 1.0 Ni: 1.0 19150 4250 1.2 inventive example Co: 1.0 3 45.0 53.9 0.1 Cu: 1.0 15950 2300 1.2 inventive example 4 45.0 52.5 0.5 Si: 2.0 16000 2400 1.15 inventive example 5 45.0 51.0 1.0 Ag: 3.0 16050 2400 1.15 inventive example 6 65.0 33.5 0.5 Zr: 1.0 19100 4200 1.15 inventive example 7 65.0 34.45 0.5 Sr: 0.05 19000 4150 1.2 inventive example 8 45.0 54.44 0.5 Sb: 0.01 15800 4050 1.25 inventive example Sr: 0.05 9 45.0 44.0 1.0 Co: 10.0 15000 2600 0.85 comparative example 10 45.0 44.0 1.0 Si: 10.0 15050 2650 0.85 comparative example 11 65.0 24.5
• the Be-Al-based alloys containing a proper amount of Mg according to the present invention serve to effectively decreased the extrusion pressure without essentially decreasing Young's modulus. It can be also clearly seen that the addition of Mg contributes to extend the lifetime of the dies.
• the present invention provides a novel Be-Al-based alloy which advantageously improve the flowability of the materials after vacuum casting, and which makes it possible to improve the formability of materials and productivity.
• the present invention is also advantageous in that, when extrusion is applied as a forming step, the extrusion pressure can be decreased and a high extrusion ratio can be used while extending the lifetime of extrusion dies.
• a Be-Al-based alloy suitably used for an actuator of a hard disk device which includes 30 to 95 wt% Be, and not more than 1.0 wt% Mg as a flowability improving element.
• the Be-Al-based alloy has an improved flowability which makes it possible to decrease extrusion pressure during extrusion stage, to extend the lifetime of the extrusion dies, and allow an inexpensive crucible material to be used.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Extrusion Of Metal (AREA)
• Forging (AREA)

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Citations (5)

• 1997
  • 1997-12-08 JP JP33703897A patent/JPH11172360A/ja active Pending
• 1998
  • 1998-12-07 EP EP98123234A patent/EP0921203A1/fr not_active Withdrawn

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