Lead-free frangible bullets and process for making same

• US 6,536,352 B1
• Filed: 05/10/2000
• Issued: 03/25/2003
• Est. Priority Date: 07/11/1996
• Status: Expired due to Fees

• Current Assignee: Delta Frangible Ammunition LLC
• Original Assignee: Delta Frangible Ammunition LLC
• Inventors: Nadkarni, Anil V., Abrams, John T.
• Primary Examiner(s): JUNG, UNSU
• Application Number:
  US09/569,060
• Time in Patent Office: 1,049 Days
• Field of Search: 419/38, 102/445, 102/506, 102/517
• US Class Current: 102/506
• CPC Class Codes: B22F 1/09 Mixtures of metallic powders
• CPC Class Codes: C22C 1/0425 Copper-based alloys
• CPC Class Codes: C22C 32/00 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 Class Codes: F42B 12/74 of the core or solid body

Abstract

Improved frangible bullets comprising powder particles of one metal bonded together by another metal wherein the metals have substantially different melting points or an alloying metal is diffused between the metal particles are manufactured by compacting the metal particles and heating under conditions to create brittle bonds.

Claims

1. A frangible bullet or projectile manufactured by admixing a lead-free matrix metal powder having a higher melting point with a lead-free metal powder having a melting point substantially lower than the higher melting point of the matrix metal powder, forming a pressed compact of said admixture of powders, and heating said pressed compact under conditions and temperatures effective such that the powder having a lower melting point reaches a molten state and wets said matrix metal powder having a higher melting point and bonds the powders, wherein the binder metal powder having a lower melting point is tin and the matrix powder having a higher melting point is copper.

2. A frangible bullet or projectile of claim 1, wherein the tin powder has a particle size of less than about 150 microns.

3. A frangible bullet or projectile of claim 1, wherein the tin powder has a particle size of less than about 44 microns.

4. A frangible bullet or projectile of claim 1, wherein the copper powder is a dispersion strengthened copper powder.

5. A frangible bullet or projectile manufactured by admixing a lead-free matrix metal powder having a higher melting point with a lead-free metal powder having a melting point substantially lower than the higher melting point of the matrix metal powder, forming a pressed compact of said admixture of powders, and heating said pressed compact under conditions and temperatures effective such that the powder having a lower melting point reaches a molten state and wets said matrix metal powder having a higher melting point and bonds the powders together, wherein the matrix metal powder having a higher melting point comprises prealloyed brass powder containing from 5 to 40 percent by weight of zinc.

6. A frangible bullet or projectile manufactured by admixing a lead-free matrix metal powder having a higher melting point with a lead-free metal powder having a melting point substantially lower than the higher melting point of the matrix metal powder, forming a pressed compact of said admixture of powders, and heating said pressed compact under conditions and temperatures effective such that the powder having a lower melting point reaches a molten state and wets said matrix metal powder having a higher melting point and bonds the powders together, wherein the matrix metal powder having a higher melting point comprises a prealloyed bronze powder containing from 2 to 7 percent by weight of tin.

7. A frangible bullet or projectile manufactured by first compacting a mixture of particles of a matrix metal powder, comprised of at least the matrix metal, and particles of a binder metal alloy powder, comprised of at least the matrix metal and an alloying metal, then heating the pressed compact under conditions to diffuse at least a portion of the alloying metal from the particles of the binder metal alloy powder and into the particles of the matrix metal powder without substantially melting any of the powder particles whereby the particles are bonded together by solid state diffusion, wherein the matrix metal is copper and the binder metal alloy powder is bronze.

8. A frangible bullet or projectile of claim 7, wherein the bronze powder has a particle size of less than about 150 microns.

9. A frangible bullet or projectile of claim 7, wherein the bronze comprises from about 10 to about 50 weight percent tin.

10. A frangible bullet or projectile of claim 7, wherein the compacted mixture comprises from about 2 to about 30 weight percent bronze.