System and method of forming nanostructured ferritic alloy

Patent metadata

Field	Value
Publication number	US-9399223-B2
Application number	US-201313953845-A
Country	US
Kind code	B2
Filing date	Jul 30, 2013
Priority date	Jul 30, 2013
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

A system for mechanical milling and a method of mechanical milling are disclosed. The system includes a container, a feedstock, and milling media. The container encloses a processing volume. The feedstock and the milling media are disposed in the processing volume of the container. The feedstock includes metal or alloy powder and a ceramic compound. The feedstock is mechanically milled in the processing volume using metallic milling media that includes a surface portion that has a carbon content less than about 0.4 weight percent.

First claim

The invention claimed is:

1. A system, comprising:
a container enclosing a processing volume;
a feedstock comprising metal or alloy powder and a ceramic compound in the processing volume; and
a metallic milling media disposed in the processing volume,
wherein the metallic milling media comprises a surface portion having a carbon content less than about 0.4 weight percent, and wherein an interior portion of the metallic milling media has an increased carbon content as compared to the surface portion.

2. The system of claim 1 , wherein the ceramic compound comprises an oxide, carbide, nitride, boride, or any combinations thereof.

3. The system of claim 1 , wherein a concentration of the ceramic compound is less than about 8 wt % of the feedstock.

4. The system of claim 3 , wherein the concentration of the ceramic compound is in a range from about 0.05 wt % to about 4 wt %.

5. The system of claim 1 , wherein the metallic milling media comprises a ferrous alloy.

6. The system of claim 5 , wherein the metallic milling media comprises a martensitic matrix.

7. The system of claim 5 , wherein the metallic milling media comprises a bainitic matrix.

8. The system of claim 1 , wherein the surface portion of the metallic milling media has a toughness greater than about 10 MPa m1/2.

9. The system of claim 1 , wherein a Rockwell hardness of the milling media is greater than about 40 HRC.

10. The system of claim 1 , wherein the carbon content of the milling media decreases from the center of the media to the surface as a function of the radial direction.

11. The system of claim 1 , wherein the milling media comprises a core-shell structure, the core comprising the interior portion and the shell comprising the surface portion.

12. The system of claim 11 , wherein a carbon content in the core is equal to or greater than about 0.4 wt % of the interior portion, and a carbon content in the shell is less than about 0.4 wt % of the surface portion.

Assignees

• Gen Electric

Inventors

• Dial Laura Cerully
• Didomizio Richard
• Alinger Matthew Joseph
• Huang Shenyan

Classifications

• C22C33/0228 Primary

  comprising other non-metallic compounds or more than 5% of graphite · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title

• B22F2009/043

  by ball milling · CPC title

• B22F2009/041

  by mechanical alloying, e.g. blending, milling · CPC title

• C22C33/0285

  with Cr, Co, or Ni having a minimum content higher than 5% · CPC title