Artifactless superelastic alloy

Patent metadata

Field	Value
Publication number	US-11268168-B2
Application number	US-201816641146-A
Country	US
Kind code	B2
Filing date	Aug 9, 2018
Priority date	Aug 22, 2017
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

The present invention provides an artifactless superelastic alloy including a Au—Cu—Al alloy, the superelastic alloy containing Cu in an amount of 20 atom % or more and 40 atom % or less, Al in an amount of 15 atom % or more and 25 atom % or less, and Au as a balance, the superelastic alloy having a bulk magnetic susceptibility of −24 ppm or more and 6 ppm or less. The Ni-free superelastic alloy of the present invention is capable of exhibiting superelasticity in a normal temperature range, and hardly generated artifacts in a magnetic field environment. The alloy can be produced by setting a casting time in a melting and casting step to a fixed time, and hot-pressing an alloy after casting to make material structures homogeneous.

First claim

The invention claimed is:

1. An artifactless superelastic alloy comprising a Au—Cu—Al alloy,
the superelastic alloy containing Cu in an amount of 20 atom % or more and 40 atom % or less, Al in an amount of 15 atom % or more and 25 atom % or less, and Au as a balance,
the superelastic alloy having a bulk magnetic susceptibility of −24 ppm or more and 6 ppm or less.

2. The superelastic alloy according to claim 1 , comprising Cu in an amount of 25 atom % or more and 35 atom % or less, Al in an amount of 18 atom % or more and 25 atom % or less, and Au as a balance.

3. The superelastic alloy according to claim 2 , having the bulk magnetic susceptibility of −8.1 ppm or more and −0.6 ppm or less.

4. A method for producing the superelastic alloy defined in claim 1 , comprising the steps of:
melting and casting a Au—Cu—Al alloy containing Cu in an amount of 20 atom % or more and 40 atom % or less, Al in an amount of 15 atom % or more and 25 atom % or less, and Au as a balance,
the melting and casting step including producing the Au—Cu—Al alloy with a molten metal solidification time set to 6.0 sec or less; and
hot-pressing the Au—Cu—Al alloy subjected to the melting and casting step at a temperature of 550° C. or higher and 650° C. or lower.

5. The method for producing the superelastic alloy according to claim 4 , comprising a homogeneity heat treatment step of heating the alloy after the hot-pressing step at a temperature of 450° C. or higher and 550° C. or lower.

6. A method for producing the superelastic alloy defined in claim 2 , comprising the steps of:
melting and casting a Au—Cu—Al alloy containing Cu in an amount of 20 atom % or more and 40 atom % or less, Al in an amount of 15 atom % or more and 25 atom % or less, and Au as a balance,
the melting and casting step including producing the Au—Cu—Al alloy with a molten metal solidification time set to 6.0 sec or less; and
hot-pressing the Au—Cu—Al alloy subjected to the melting and casting step at a temperature of 550° C. or higher and 650° C. or lower.

Assignees

• Tokyo Inst Tech
• Tanaka Precious Metal Ind

Inventors

• Hosoda Hideki
• Umise Akira
• Goto Kenji

Classifications

• C22F1/14

  of noble metals or alloys based thereon · CPC title

• C22C1/02 Primary

  by melting {(C22C1/1036 takes precedence)} · CPC title

• A61L31/02

  Inorganic materials · CPC title

• C22C30/02

  containing copper · CPC title

• B22D27/04

  Influencing the temperature of the metal, e.g. by heating or cooling the mould · CPC title