US3298829A - Beryllium product and method of making same - Google Patents

Description

United States Patent Cfitice 3,298,829 Patented Jan. 17, 1967 3,298,829 BERYLLIUM PRODUCT AND METHOD OF MAKING SAME Charles J. Havel, Allentown, Pa., assignor to The Beryllium. Corporatiomkeading, Pa, a corporation of Delaware No Drawing. Filed June 18, 1965, Ser. No. 465,167

5 Claims. (Cl. 75-212) Another object of the present invention is to produce a beryllium metal having superior elastic modulus, high precision elastic limit, and high tensile strength which will not experience grain growth during fabrication.

A further object of the instant invention is to set forth a process of producing high strength by beryllium alloys wherein the alloy is characterized by a beryllide of the alloying metal at the interface between the particles, and surrounding each particle of beryllium powder so as to inhibit grain growth and reinforce the beryllium matriX.

A more specific object of the instant invention is to set fortha process whereby beryllium powder is coated with a thin coating of a metal which will form a beryllide when pressed into shape under heat.

Other objects and advantages of the invention will become more apparent from the following detailed description and examples.

it has been found that high strength beryllium metal can be formed without sacrificing low bulk density and at the same time having superior elastic modulus, high precision elastic limit, and high tensile strength by coating beryllium powder with a metal capable of forming a beryllide and subsequently hot-pressing the powders to form the new beryllium metal.

The beryllium powder used is of a size of about 4 to 74 microns, but preferably in the order of 4 to microns. This powder is coated with a metal capable of forming a beryllide in any suitable manner, such as for example in the process disclosed in copending application Serial No. 442,240, filed March 22, 1965, which is a continuation-in part of application Serial No. 260,857, now abandoned. In practice, coatings of up to 50 Angstroms have been found suitable. This powder when subjected to pressure and heat forms a beryllide on the surface of each individual particle and at the interface between particles which inhibits grain growth and reinforces the beryllium matrix.

Typical of the metals which form beryllides are chromium, copper, nickel, columbium, molybdenum, cobalt and iron. The pressure can vary from 350 pounds per square inch to 2000 pounds per square inch, and the temperature for pressing may vary between 1900 F. to 2200 F. The pressure and temperature utilized as well as the duration of pressing may vary dependent upon the physical characteristics, such as size of the shape being produced.

Some typical examples illustrating the compositions, processes and characteristics of the beryllium metal are the'following';

Example 1 Nominal 11 micron beryllium powder was vacuum hotpressed at 2000" F. and 2000 psi.

The chemistry of both the treated powder and the resultant pressing are:

By Analysis, percent Constituent Treated Powder Hot Pressed Balance Balance 1 Xray diffraction.

Example I when hot-pressed and tested gave the following properties:

Test Direction 2% Y.S. Peg'ient Nil 1 Tested with cxtensoineter, premature notch failure, modulus equals 55.6)(10 and 52BX10 respectively.

2 Not determined due to gage slippage.

3 Tested without extensometer.

L Longitudinal specimen.

'1 Transverse specimen.

Some other examples showing beryllium metals in which the powders were coated with chromium are the follow ing:

TAB LE I [Typical chemistry of Be'Cr] Constituent Example No. II Example No. III

. 26S 438 113 127 027 034 095 L 001 015 L 001 210 235 027 039 Balance liala nce Note-L indicates less than.

TABLE 11 [Mechanical properties of Be-Cr (as pressed)] UTS (K s.i.) 1 niieroinch 2 microinches PEL (p.s.i.) PEL (p.s.i.)

No. I 104. 0 26, 500 29. 750 103. 0 22, 37. 700

Example I was subjected to solution annealing after pressing, and gave the following results.

TABLE III [Property response of Example I to solution annealing] [Hardness response to solution annealingair cooling] Tem- Hardness RB Example I perature, Time Sample No. F.

Before After Change 2, 175 1 101 100 2, 175 2 102 97 2, 175 4 101 95 2, 175 8 100 93 2, 175 16 102 89 2, 175 32 101 88 2, 200 l 101 97 2, 200 2 99 94 2, 200 4 101 94 2, 200 8 101 90 ll 2, 200 21 104 92 -12 The following tests were made to show the superior strength of metal-coated beryllium powder over a typical surface-oxidized beryllium powder:

Example V Composition A.-Nominal 11 micron beryllium powder was chrome-coated and vacuum hot-pressed at 2000 F. and 2000 p.s.i. yielding a density of 1.876 gr./cc. The powder and hot-pressed chemistries were:

Powder, percent Hot-Pressed,

percent 274 231 130 110 029 040 016 017 031 055 111 095 190 210 Balance Balance 1 X-ray difiraetion.

Composition B.Ball milled beryllium powder, surface oxidized to a minimum of 4.25% BeO and containing no alloy coating was vacuum hot-pressed at 2000 F. and 2000 p.s.i. yielding a density of 1.892 gr./cc. Weighted average powder particle size per Coulter Counter was 8.2

The above examples were tested and showed the following results:

TABLE V UTS YS Elongation PEL (p.s.i.) (p.s.i.) (percent) (p.s.i.)

Composition A 104, 000 Nil 22,125 Composition B 61, 900 56, 700 0. 75 7, 500

TABLE VI Material Original Grain Grain Size alter Size 220 F.2 hours Composition A 7 microns 7 Composition B 9 microns 13. 3

Other data substantiating the inhibiting effect of the beryllide film is listed below for Composition A.

Hours at 2175" F. Original Size Final Size Final in Mierons in Mierons Hardness-Rn It appears that after sixteen hours, full solutioning of the beryllide occurs, as evidenced by the very slight change in hardness between 16 and 32 hours, and the beryllide has diffused into the beryllium matrix. Once the beryllide has diffused into the matrix, grain growth occurs. For example, note increase from 7.4 to 12.4 after 32 hours at 2175 F.

In view of the foregoing, it is apparent that there is provided a new and improved process for producing heat-treatable beryllium metal of superior mechanical properties without sacrificing the weight advantage of beryllium. As set forth above, the process involves the coating of beryllium powders with a metal which will form a beryllide on the surface of each individual particle and at the interface of said particles when pressed under heat. This beryllide interface prevents grain growth of the beryllium metal, and reinforces the beryllium matrix by providing a beryllide network throughout the beryl lium pressing, thus increasing the strength of the beryllium product.

This process provides a beryllium product with high strength, a high precision elastic limit, and a superior modulus of elasticity. The precision elastic limit relates to the dimensional stability of the metal and is equivalent to the amount of stress which will cause one millionth of an inch permanent deformation.

As stated above, it is within the scope of this invention to utilize any metal for coating the powders which will form a. beryllide on the surface of the powders when pressed.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperate equivalents are therefore intended to be embraced by those claims.

What is claimed is;

1. A method of producing a beryllium product characterized by high strength comprising, coating beryllium powders of a size of from 4 to 74 microns with a metal selected from the group consisting of chromium, copper, nickel, columbium, molybdenum, cobalt and iron, and hot pressing the coated powders at a pressure of from 350 to 5 6 2000 psi. and at a temperature of from 1900 F. to References Cited by the Examiner 2200 F. to form a beryllium product. UNITED STATES PATENTS 2. The process of claim 1, wherein the pressed beryllium product is subsequently heat-treated to modify the 3150975 9/1964 Beaver et 75-214 strength of the product. 5 FOREIGN PATENTS 3. The process of claim 1, wherein the powders are 527618 10/1940 Great Britain from 4 to 15 microns.

4. The process of claim 1, wherein the coating has a CARL D QUARFORTH Primary Examiner.

thickness of 50 Angstrorns or less.

5. The process of claim 2, wherein the pressed beryl- 10 DEWAYNE RUTLEDGE, Exammefi lium product is heat-treated at from 2000 F. to 2200 F. R, L GRUDZIECKI, Assistant for from 1 to 32 hours.

Claims (1)

1. A METHOD OF PRODUCING A BERYLLIUM PRODUCT CHARACTERIZED BY HIGH STRENGTH COMPRISING, COATING BERYLLIUM POWDERS OF A SIZE OF FROM 4 TO 74 MICRONS WITH A METAL SELECTED FROM THE GROUP CONSISTING OF CHROMIUM, COPPER, NICKEL COLUMBIUM, MOLYBDENUM, COBLAT AND IRON, AND HOT PRESSING THE COATED POWDERS AT A PRESSURE OF FROM 350 TO 2000 P.S.I. AND AT A TEMPERATURE OF FROM 1900*F. TO 2200*F. TO FORM A BERYLLIUM PRODUCT.