Bimodal Metal Matrix Nanocomposites and Methods of Making

Patent metadata

Field	Value
Publication number	US-2016101468-A1
Application number	US-201414156935-A
Country	US
Kind code	A1
Filing date	Jan 16, 2014
Priority date	Jan 16, 2013
Publication date	Apr 14, 2016
Grant date	—

Abstract

A bimodal metal nanocomposite of ceramic nanoparticles in a metal or metal alloy matrix has a microstructure showing a first “hard” phase containing the ceramic nanoparticles in the metal or metal alloy matrix, and a second “soft” phase comprising only the metal or metal alloy with few or no ceramic nanoparticles. The stiffness and yield strength of the bimodal metal nanocomposite is significantly increased compared to the metal or metal alloy alone, while the ductility of the metal or metal alloy is retained. A process for making the bimodal metal matrix nanocomposite includes milling a powder mixture of micrometer-size metal flakes and ceramic nanoparticles for a time sufficient to embed the ceramic nanoparticles into the metal flakes.

First claim

What is claimed is:

1 . A process for making a bimodal metal matrix nanocomposite, comprising the steps of:
milling a powder mixture comprising micrometer-size metal flakes and ceramic nanoparticles for a time sufficient to embed a majority of the ceramic nanoparticles into the metal flakes; and sintering the milled metal flakes with embedded ceramic nanoparticles to produce a nanocomposite having a bimodal microstructure.

2 . The process of claim 1 , wherein the metal flakes include at least one of magnesium, aluminum, copper, iron, tin, titanium, and nickel.

3 . The process of claim 1 , wherein the metal flakes comprise at least one of magnesium and magnesium alloy with a flake morphology.

4 . The process of claim 1 , wherein the metal flakes have a mean particle size of from about 1 to about 250 micrometers.

5 . The process of claim 1 , wherein the ceramic nanoparticles are formed of at least one of silicon carbide, silicon nitride, aluminum oxide, boron carbide, titanium nitride, titanium oxide, zirconium oxide, yttrium oxide, and cerium oxide.

6 . The process of claim 1 , wherein the ceramic nanoparticles have a mean particle size of from about 20 nm to about 100 nm.

7 . The process of claim 1 , wherein the volume fraction of ceramic nanoparticles in the powder mixture is greater than 5% based on the powder mixture volume.

8 . The process of claim 1 , further comprising adding a grinding aid to the powder mixture prior to or during the milling step.

9 . The process of claim 8 , wherein the grinding aid comprises a surfactant.

10 . The process of claim 8 , wherein the grinding aid includes at least one of stearic acid and ethanol.

11 . The process of claim 8 , wherein 1% to 5% grinding aid is added based on the weight of the powder mixture.

12 . The process of claim 11 , wherein the grinding aid includes at least one of stearic acid and ethanol.

13 . The process of claim 1 , wherein the milling step is conducted in an inert atmosphere.

14 . The process of claim 1 , wherein the milling step is conducted in an argon atmosphere.

15 . The process of claim 1 , wherein the milling step is conducted with ceramic balls having a density less than the density of the ceramic nanoparticles.

16 . The process of claim 15 , wherein the milling step is conducted with a ratio of ball weight to the powder mixture weight in a range of from about 5:1 to about 15:1.

17 . The process of claim 16 , wherein the powder mixture is milled for a time and milling speed sufficient to embed greater than 95% of the ceramic nanoparticles into the metal flakes.

18 . The process of claim 1 , wherein the powder mixture is milled in a planetary miller at room temperature.

19 . The process of claim 18 , wherein the powder mixture is milled for 10 to 20 hours with a milling speed between 150 rpm to 200 rpm.

20 . The process of claim 1 , further comprising adding surfactant to the milled powder mixture to aid in recovery of the milled metal flakes with embedded ceramic nanoparticles from the mill.

21 . The process of claim 1 , wherein the milled metal flakes with embedded ceramic nanoparticles are sintered in a vacuum-hot-press furnace.

22 . The process of claim 21 , wherein the vacuum-hot-press furnace operates at about 90% of the metal flake melting temperature.

23 . The process of claim 1 , wherein the milled metal flakes with embedded ceramic nanoparticles are sintered to greater than 98% of theoretical density.

24 . A bimodal metal nanocomposite made by the process of claim 1 .

25 . The bimodal metal nanocomposite of claim 24 , wherein the metal flakes comprise at least one of magnesium metal and magnesium alloy.

26 . The bimodal metal nanocomposite of claim 25 , having greater than 5 vol % ceramic nanoparticles.

27 . The bimodal metal nanocomposite of claim 26 having a first phase and a second phase, the first phase comprising the ceramic nanoparticles in a metal or alloy matrix, and the second phase comprising the metal or alloy with few or no ceramic nanoparticles.

28 . A process for making a bimodal metal matrix nanocomposite, comprising the step of: milling a powder mixture comprising micrometer-size metal flakes and ceramic nanoparticles for a time sufficient to embed a majority of the ceramic nanoparticles into the metal flakes.

29 . The process of claim 27 , wherein the metal flakes comprise at least one of magnesium and magnesium alloy.

Assignees

• Univ Central Florida Res Found

Inventors

• An Linan
• Liu Jinling

Classifications

• B22F1/068

  Flake-like particles · CPC title

• B22F1/102

  Metallic powder coated with organic material · CPC title

• C22C32/0063

  based on SiC · CPC title

• C22C32/00

  Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ · CPC title

• B22F1/0062

  Operations & Transport · mapped topic