High-strength high-toughness amorphous zirconium alloy

Details High-strength high-toughness amorphous zirconium alloy High-strength high-toughness amorphous zirconium alloy

2000-06-29

2003-02-18

Wyszomierski, George (Department: 1742)

Metal treatment

Stock

Amorphous, i.e., glassy

C148S421000, C420S423000

Reexamination Certificate

active

06521058

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to amorphous Zr alloys which have a high glass-forming ability and excellent strength and toughness.
RELATED ART
Amorphous metal materials having various forms, such as thin ribbons, filaments, particles and the like, can be obtained by rapidly cooling molten alloys. A thin-ribbon-shaped amorphous alloy is easily manufactured by means of a single roll method, a twin-roller method, an in-rotating water melt spinning method and the like, in which a large cooling speed can be obtained. Conventionally, various amorphous alloys have been provided using alloys of Fe, Ni, Co, Pd, Cu, Zr or Ti; those amorphous alloys show properties unique to amorphous alloys such as high corrosion resistance, high strength, and the like. Especially, an amorphous Zr alloy is expected to be applied to the fields of structural materials, medical materials and chemical materials as a new kind of amorphous alloy having an outstanding high glass-forming ability compared to other amorphous alloys.
However, shapes of the amorphous alloys manufactured by means of previously mentioned methods are limited to thin ribbons or thin wires; it is difficult to process the amorphous alloys of those shapes into a form of final products. Therefore, the uses of such amorphous alloys are limited in industry.
On the other hand, it is known that when amorphous alloys are heated, some of alloys
On the other hand, it is known that when amorphous alloys are heated, some of alloys undergo transition to a phase of supercooled liquid before crystallization and indicate a decline in viscosity. For example, when heated at a speed of 40° C. per minute, an amorphous Zr alloy is observed to remain in the supercooled liquid phase for a range of temperature of the maximum of 120° C. before crystallization starts (see Mater. Trans., JIM, Vol. 32, (1991), 1005).
In the supercooled liquid phase, the low viscosity of the amorphous alloy allows one to form it into a given shape by closed squeeze casting process and the like; for example, gears can be formed of an amorphous alloy (see Nikkan Kogyo Shinbun, Nov. 12, 1992). Hence, amorphous alloys having a wide range of the supercooled liquid phase can be said to provide excellent workability. Among such amorphous alloys having a wide range of supercooled liquid phase, an amorphous Zr—Al—Ni—Cu alloy has a range of temperature of 100° C. as the supercooled liquid phase, therefore, is considered to be an amorphous alloy with excellent applicability, such as high corrosion resistance (see Japanese Examined Patent Application Publication H07-122120).
The glass-forming ability and a method for manufacturing of those amorphous alloys have been further improved. As a result, Japanese Laid-Open Patent Application Publication H08-74010 discloses development of an amorphous Zr alloy having a 100° C. range for the supercooled liquid phase and a thickness exceeding 5 mm. Also, various manufacturing methods to improve mechanical characteristics of the amorphous alloys have been tried (Japanese Laid-Open Patent Application Publications: 2000-24771, 2000-26943, 2000-26944); however, these amorphous Zr alloys do not provide sufficient mechanical characteristics as structural materials.
DETAILS OF THE INVENTION
Problems to be Solved
The amorphous Zr alloy described previously has a high glass-forming ability and relatively good strength characteristics due to the range of the supercooled liquid phase above 100° C. Nonetheless, attempts to improve its mechanical characteristics have been made only in the manufacturing method; attempts to improve the composition of alloys has not been made.
Solution of the Problems
Intending to provide an amorphous Zr alloy material having improved strength and toughness without impairing a temperature range for the supercooled liquid phase and a size enabling application to industrial use, inventors of the present invention studied the above issues. They discovered the an amorphous Zr alloy having high strength and toughness as well as excellent glass-forming ability can be obtained by melting an alloy in which a given amount of M element (one or two or more elements selected from a group consisting of Ti, Nb and Pd) is added to a Zr—Al—Ni—Cu—M alloy of a given composition, followed by rapid cooling for solidification.
In other words, the present invention intends to provide an amorphous Zr alloy which contains non-crystalline phase of 90% or higher by volume wherein the alloy has a composition expressed as Zr—Al
a
—Ni
b
—Cu
c
13
M
d
(in this expression terms are defined as follows:
M: one or two or more elements selected from a group consisting of Ti, Nb and Pd;
a, b, c, and d: atomic % wherein:
5≦a≦10;
30≦b+c≦50;
b/c≦1/3;
0<d≦7;
remainder: Zr and inevitable impurities).
Further, a “range of the supercooled liquid phase” is defined as a difference between a glass transition temperature, obtained by differential scanning thermogravimetry at a speed of heating of 40° C. per minute, and a crystallization temperature. The “range of the supercooled liquid phase” indicates resistance to crystallization, that is, stability of glass-forming ability. The alloy of the present invention has a range of the supercooled liquid phase over 100° C.


REFERENCES:
patent: 5032196 (1991-07-01), Masumoto et al.
patent: 6010580 (2000-01-01), Dandliker et al.
patent: 7-122120 (1995-12-01), None
patent: 8-74010 (1996-03-01), None
patent: 2000-24771 (2000-01-01), None
patent: 2000-26943 (2000-01-01), None
patent: 2000-26944 (2000-01-01), None
Patent Abstract of Japan, Pub. No. JP-07-062502, Mar. 7, 1995—See PCT search rpt.
Patent Abstract of Japan, Pub. No.JP-07-188877, Jul. 25, 1995—See PCT search rpt.
Patent Abstract of Japan, Pub. No.JP-08-199318, Aug. 6, 1996—See PCT search rpt.
Patent Abstract of Japan, Pub. No.JP-10-186176, Jul. 14, 1998—See PCT search rpt.
Patent Abstract of Japan, Pub. No.JP-08-074010, Mar. 19, 1996.
Patent Abstract of EP0433670, Jun. 26, 1991.
Nikkan Kogyo Shinbun, Nov. 12, 1992 (see spec. p. 2).
Tao Zhang et al., Material Transaction, JIM, vol. 32, No. 11 (1991), pp. 1005 to 1010, “Amorphous Zr-A1-TM (TM═Co, Ni, Cu) Alloys with Significant Supercooled Liquid Region of Over 100 K”.

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