Metal treatment – Stock – Aluminum base
Reexamination Certificate
1999-10-28
2002-06-11
King, Roy (Department: 1742)
Metal treatment
Stock
Aluminum base
C420S543000
Reexamination Certificate
active
06402860
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an aluminum alloy and a method for manufacturing an aluminum-alloy member and, more particularly, to an aluminum alloy combining good forgeability and high hardness and a method for manufacturing an aluminum-alloy member combining good forgeability and high hardness.
2. Description of the Background Art
High-strength aluminum alloys have been in use in recent years that are produced by adopting a rapid solidification technique.
For instance, a published Japanese patent application Tokukaihei 1-275732 has disclosed that rapid solidification of a multi-element alloy expressed by a general formula A
a
M
b
X
c
produces a nanocrystalline aluminum alloy having such mechanical properties as a tensile strength of 853 to 1,009 MPa, a yield strength of 804 to 941 MPa, and a hardness HV of 200 to 1,000. In the above formula Al
a
M
b
X
c
, (1) “M” means one or more kinds of metal elements selected from the group consisting of chrome(Cr), manganese(Mn), iron(Fe), cobalt(Co), nickel(Ni), copper(Cu), zirconium(Zr), titanium(Ti), magnesium(Mg), and silicon(Si), (2) “X” means one or more kinds of metal elements selected from the group consisting of yttrium(Y), lanthanum(La), cerium(Ce), samarium(Sm), neodymium(Nd), niobium(Nb), and mischmetal(Mm), and (3) “a”, “b”, and “c” mean an atomic percent, “a” lying in the range of 50 to 95 atm. %, “b” in the range of 0.5 to 35 atm. %, and “c” 0.5 to 25 atm. %.
Another published Japanese patent application Tokukaihei 6-184712 has disclosed an aluminum alloy having the composition expressed by a general formula Al
a
Ln
b
M
c
, where (1) “Ln” means one or more kinds of metal elements selected from the group consisting of mischmetal, yttrium, lanthanum, cerium, samarium, neodymium, hafnium, niobium, and tantalum, (2) “M” means one or more kinds of metal elements selected from the group consisting of vanadium, chrome, manganese, iron, cobalt, nickel, copper, zirconium, titanium, molybdenum, tungsten, calcium, lithium, magnesium, and silicon, and (3) “a”, “b”, and “c” mean an atomic percent, “a” lying in the range of 50 to 97.5 atm. %, “b” in the range of 0.5 to 30 atm. %, and “c” 0.5 to 30 atm. %. The aluminum alloy is a rapidly solidified aluminum alloy that has a cellular composite structure in which 5 to 50 vol. % amorphous phases surround nanocrystalline phases. The aluminum alloy is subjected to plastic working at a temperature higher than the crystallization temperature of the amorphous phase. Intermetallic compounds comprising two or more kinds of the above-described Al, “Ln”, and “M” are dispersed in the nanocrystalline matrix to form a structure having such mechanical properties as a tensile strength of 760 to 890 MPa and an elongation of 5.5 to 9.0%.
However, the aluminum alloy disclosed in the application Tokukaihei 1-275732 has poor ductility and toughness, though it has very high tensile strength and hardness. Because this lack of sufficient ductility and toughness allows easy generation of cracks at the time of processing such as forging and upsetting, it is difficult to perform near-net-shape forging with complicated shapes.
When forging is carried out by exploiting its superplasticity resulting from its nanocrystallinity, it is possible to impart complicated shapes. However, its poor ductility and toughness requires prolonged time for a single step of forging, causing a problem of reduced production efficiency, and hence an increase in manufacturing costs. Such a problem becomes serious when forming ornamental components that require complicated, fine shapes such as embossed letters on the surface.
Although the aluminum alloy disclosed in the application Tokukaihei 6-184712 ensures a certain amount of ductility, it does not have sufficient mechanical properties to undergo near-net-shape forging with complicated shapes. In addition to that, because it uses material powders in which amorphous layers are formed, there is a problem of increased material cost.
SUMMARY OF THE INVENTION
The present invention is aimed at solving the above-described problems. An object of the present invention is to offer an aluminum alloy that not only has high hardness accompanied by balanced ductility but also has high toughness and superior processability.
Another object of the present invention is to offer a method for manufacturing an aluminum-alloy member that not only has high hardness accompanied by balanced ductility but also has high toughness and superior processability.
The first aspect of the present invention offers an aluminum alloy that comprises (1) not less than 0.1 wt. % and not more than 8 wt. % Constituent A comprising one or more kinds of elements selected from the group consisting of titanium (Ti), vanadium (V), hafnium (Hf), and zirconium (Zr), (2) not less than 0.1 wt. % and not more than 20 wt. % Constituent B comprising one or more kinds of elements selected from the group consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), mischmetal (Mm), calcium (Ca), strontium (St), and barium (Ba), and (3) not less than 0.1 wt. % and not more than 20 wt. % Constituent C comprising one or more kinds of elements selected from the group consisting of magnesium (Mg) and lithium (Li).
The second aspect of the present invention offers another aluminum alloy that comprises (1) not less than 0.1 wt. % and not more than 5 wt. % Constituent D comprising one or more kinds of elements selected from the group consisting of niobium (Nb), molybdenum (Mo), silver (Ag), iron (Fe), cobalt (Co), tantalum (Ta), and tungsten (W), (2) not less than 0.1 wt. % and not more than 20 wt. % Constituent B comprising one or more kinds of elements selected from the group consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), mischmetal (Mm), calcium (Ca), strontium (St), and barium (Ba), and (3) not less than 0.1 wt. % and not more than 20 wt. % Constituent C comprising one or more kinds of elements selected from the group consisting of magnesium (Mg) and lithium (Li).
The third aspect of the present invention offers a method for manufacturing an aluminum-alloy member made of the following aluminum alloy: The aluminum alloy comprises (1) not less than 0.1 wt. % and not more than 8 wt. % Constituent A comprising one or more kinds of elements selected from the group consisting of titanium (Ti), vanadium (V), hafnium (Hf), and zirconium (Zr), (2) not less than 0.1 wt. % and not more than 20 wt. % Constituent B comprising one or more kinds of elements selected from the group consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), mischmetal (Mm), calcium (Ca), strontium (St), and barium (Ba), and (3) not less than 0.1 wt. % and not more than 20 wt. % Constituent C comprising one or more kinds of elements selected from the group consisting of magnesium (Mg) and lithium (Li). First, a preform comprising the aluminum alloy is produced. Next, the preform is heated up to a temperature not lower than 200° C. and not higher than 600° C. at a temperature rising rate of not less than 2° C./sec and not more than 200° C./sec. Then, the heated preform is subjected to hot-working.
The fourth aspect of the present invention offers a method for manufacturing an aluminum-alloy member made of the following aluminum alloy: The aluminum alloy comprises (1) not less than 0.1 wt. % and not more than 5 wt. % Constituent D comprising one or more kinds of elements selected from the group consisting of niobium (Nb), molybdenum (Mo), silver (Ag), iron (Fe), cobalt (Co), tantalum (Ta), and tungsten (W), (2) not less than 0.1 wt. % and not more than 20 wt. % Constituent B comprising one or more kinds of elements selected from the group consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), mischmetal (Mm), calcium (Ca), strontium (St), and barium (Ba), and (3) not less than 0.1 wt. % and not more than 20 wt. % Constituent C comprising one or more kinds of elements selected from the group consisting of magnesium (Mg) and lithium (Li).
Hashikura Manabu
Hattori Hisao
Kaji Toshihiko
Takeda Yoshinobu
Combs-Morillo Janelle
King Roy
McDermott & Will & Emery
Sumitomo Electric Industries Ltd.
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