# US 9,039,849 B2 · Preparation method of nanocrystalline titanium alloy at low strain

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- Number: US 9,039,849 B2
- Document ID: US9039849B2
- Status: Granted
- Kind: B2
- Application number: 13/394,195
- Filed: 2009-11-30
- Published: 2012-06-28
- Granted: 2015-05-26
- Earliest claimed: 2009-09-07
- Assignees: Postech Academy-Industry Foundation
- Applicants: Chan Hee Park; Chong Soo Lee; Sung Hyuk Park; Young Soo Chun
- Inventors: Chan Hee Park; Chong Soo Lee; Sung Hyuk Park; Young Soo Chun
- Web page: https://patentgrep.com/patent/US9039849B2

## CPC

- C22C 14/00: Alloys based on titanium
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

Provided is a method of preparing a nanocrystalline titanium alloy at low strain to have better strength. The present invention is characterized in that an initial microstructure is induced as martensites having a fine layered structure, and then a nanocrystalline titanium alloy is prepared at low strain by optimizing process variables through observation of the effects of strain, strain rate, and deformation temperature on the changes in the microstructure.

## Claims

### Claim 1

A method of preparing a nanocrystalline titanium alloy, the method comprising;
segmenting a martensite structure haying a layered structure into a fine equiaxed structure having a size range of 200 nm to 400 nm by rolling under conditions that a deformation temperature ranges from 575° C. to 625° C., a strain rate ranges from 0.07 to 0.13 s−1, and a strain ranges from 0.9 to 1.8,
wherein a dynamic spheroidization is generated when the layered structure of the martensite structure is entirely segmented into the fine equiaxed structure.

### Claim 2 (depends on 1)

The method of claim 1, wherein the deformation temperature is 600° C., the strain rate is 0.1 s−1, and the strain is 1.4.

### Claim 3 (depends on 1)

The method of claim 1, wherein the martensite structure is obtained from an initial microstructure of a Ti-13Nb-13Zr alloy by water quenching the initial microstructure after being maintained at 800° C. for 30 minutes.