Process for producing shaped article

Details Process for producing shaped article Process for producing shaped article

1999-09-02

2001-08-14

Jenkins, Daniel (Department: 1742)

Powder metallurgy processes

Powder metallurgy processes with heating or sintering

Making composite or hollow article

C419S006000, C419S007000, C419S008000, C419S009000, C419S012000, C419S013000, C419S014000, C419S019000, C419S035000

Reexamination Certificate

active

06274082

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing a shaped article, and more particularly, to a process for producing an aluminum alloy shaped article that has an advantageous combination of plural excellent properties, such as strength, rigidity, abrasion resistance and surface hardness, and can be used in a wide field, such as structural materials and members for machines, structural materials and members for automobiles, and members for sport goods.
2. Description of the Prior Art
Various improvements have conventionally been made on an aluminum alloy for the purpose of improving its strength, heat resistance, abrasion resistance, rigidity and the like. Of those improved materials, particle- or fiber-reinforced composite materials, powder metallurgical materials produced, for example, by rapid-solidification, mechanical alloying or the like, are the representative examples thereof. However, those materials have the problems that if strength, abrasion resistance, heat resistance and the like are improved, toughness decreases, and if the concentration or volume rate of various alloying elements or reinforcing particles increases, corrosion resistance decreases. Further, aluminum alloy materials having both abrasion resistance and high strength have not yet been developed. For example, a high strength alloy produced by a rapid-solidification method including gas atomizing is developed. However, this alloy is satisfied with strength characteristics, but it has been difficult to further impart to the alloy other properties such as abrasion resistance, in addition to strength characteristics. Further, gradient materials are proposed in which a mixing ratio of various alloys or particles is continuously changed therein, but such materials are still under investigation. Also, in cladding or co-extrusion method, which is a composite technique for a molten metal material, an entire surface of a first material is covered with a second material. Thus, even unnecessary parts are covered, and the characteristics of the first material cannot sufficiently be exhibited. This may be disadvantageous from the standpoint of costs. In addition, a method by welding such as brazing involves increase in the number of steps, making it difficult to shift the method to automation.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned disadvantages involved in the prior art techniques. Accordingly, an object of the present invention is to readily provide an alloy material having an advantageous combination of plural properties, such as high strength and abrasion resistance, etc., by maximally utilizing merits of a powder metallurgical method.
The present invention provides a shaped article formed from a consolidated powder material and having a plurality of excellent properties in combination as a whole by combining an abrasion resistant material, a self-lubricant material or the like with an aluminum alloy used as a base material in such an arrangement that the aluminum alloy has properties required in the intended use or is improved in such properties. More specifically, the present invention is directed to:
(1) A process for producing a shaped article, comprising:
preparing a first powder having high strength and rigidity after completion of forming, and a second powder having abrasion resistance and surface hardness after completion of forming;
compacting those powders to provide a forming material comprising a base part comprising the first powder and a supplemental part comprising the second powder; and
forming the forming material into a shaped article by plastic processing in which the base part and the supplemental part have different characteristics.
(2) A process for producing a shaped article as defined in item (1), wherein the second powder is arranged on a surface of the first powder, and those powders are simultaneously compressed to form the forming material.
(3) A process for producing a shaped article as defined in item (1), wherein the first powder is consolidated with a cold isostatic press to form the base part, the second powder is placed on the surface of the base part, and those are compacted into the forming material.
(4) A process for producing a shaped article as defined in item (1), wherein the plastic processing is any one of extrusion, forging or rolling.
(5) A process for producing a shaped article as defined in item (1), wherein the first powder consists of at least one rapidly-solidified alloy powder consisting of a composition represented by any one of the following chemical formulae (I) to (IV).
(6) A process for producing a shaped article as defined in item (1), wherein the first powder consists of a quasi-crystal alloy powder consisting of a composition represented by the following formula (V).
(7) A process for producing a shaped article as defined in item (1), wherein the second powder consists of at least one member selected from the group consisting of Al
2
O
3
, Si
3
N
4
, BN, SiC, Al
4
C
3
, Al
8
B
2
O
15
and B
2
O.
(8) A process for producing a shaped article as defined in item (1), wherein the second powder is a mixture of (a) at least one selected from the group consisting of a rapidly-solidified alloy powder consisting of a composition represented by any one of the following formulae (I) to (IV) and a quasi-crystal alloy powder consisting of a composition represented by the following formula (V) and (b) at least one alloy powder selected from the group consisting of Al
2
O
3
, Si
3
N
4
, BN, SiC, Al
4
C
3
, Al
8
B
2
O
15
and B
2
O.
(9) A process for producing a shaped article as defined in item (1), wherein the first powder consists of at least one rapidly-solidified alloy powder consisting of a composition represented by any one of the following formulae (I) to (IV), and the second powder consists of a quasi-crystal alloy powder consisting of a composition represented by the following formula (V).
Rapidly-solidified alloy powder: General Formula:
Al
a
M1
b
X
e
,  (I)
Al
a
M1
(b-c)
M2
c
X
e
,  (II)
Al
a
M1
(b-d)
M3
d
X
e
,  (III)
and
Al
a
M1
(b-c-d)
M2
c
M3
d
X
e
  (IV)
wherein:
M1: at least one element selected from the group consisting of Mn, Fe, Co, Ni and Mo;
M2: at least one element selected from the group consisting of V, Cr and W;
M3: at least one element selected from the group consisting of Li, Ca, Mg, Si, Cu and Zn;
X: at least one element selected from the group consisting of Nb, Hf, Ta, Y, Zr, Ti, Ag, rare earth elements and misch metal (hereinafter, referred to as “Mm”) which is a mixture of rare earth elements; and
a, b, c, d and e are, in atomic %, 75≦a≦97, 0.5≦b≦15, 0.1≦c≦5, 0.5≦d≦5, and 0.5≦e≦10.
More preferably, the rapidly-solidified alloy powder has a structure comprising Al crystals having an average particle size of 0.005 to 1 &mgr;m, and intermetallic compound particles having an average particle size of 0.001 to 0.1 &mgr;m.
Ouasi-crystal alloy powder:
Al
bal
M4
x
M5
y
  General Formula (V)
wherein:
M4: at least one element selected from the group consisting of Mn, Cr, V, Mo and W;
M5: at least one element selected from the group consisting of Fe, Co, Ni, Cu, Zr, Mg, Ti, Hf, Si, Y, rare earth elements and Mm;
x and y are, in atomic %, 0.5≦x10 and 0.5≦y10. The quasi-crystal alloy powder contains at least one selected from the group consisting of quasi-crystals consisting of an icosahedral phase, a regular decagonal phase or a similar crystal phase akin thereto (hereinafter “approximant phase”) in the range of 30 to 90% by volume.
The quasi-crystal alloy powder more preferably has a structure which comprises quasi-crystals having a particle size of 1 &mgr;m or less and Al crystals having an average particle size of 10 &mgr;m or less.


REFERENCES:
patent: 4630692 (1986-12-01), Ecer
patent: 5967248 (1999-10-01), Drake et al.

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