AlBeMet is the

trade name A trade name, trading name, or business name, is a pseudonym used by companies that do not operate under their registered company name. The term for this type of alternative name is a "fictitious" business name. Registering the fictitious name w ...

for a

beryllium Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form mi ...

and

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

metal matrix

composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...

derived by a

powder metallurgy Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes can reduce or eliminate the need for subtractive processes in manufacturing, lowering material losses and ...

process. AlBeMet AM162 is manufactured by Materion Corporation Brush Beryllium and Composites (formerly known as Brush Wellman). AlBeMet is formed by hot consolidating gas atomized prealloyed powder. Each powder particle contains aluminium between beryllium dendrites producing a uniform microstructure. Aluminium-beryllium metal matrix composite combines the high modulus and low density characteristics of beryllium with the fabrication and mechanical property behaviors of aluminium. Due to weight advantage, Be-Al alloys are used in aerospace and satellite applications.

Basic properties

The composition of AlBeMet AM162 by relative weight is 38% Al, 62% Be. AlBeMet has a

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of 2.071 g/cm³ (0.07482 lb/in³).

Mechanical properties

The mechanical properties of AM162 have been characterized in all three-product forms with the extruded product form of AlBeMet having a significant design database. The extruded bar is fabricated by cold isostatic pressing (CIPing) the isotropic spherical aluminium-beryllium powder into semi-dense billets and then canning the billet for subsequent extrusion with a minimum of a 4:1 reduction ratio. Mechanical properties are minimum values at room temperature. Wrought mechanical properties for extrusions are in the longitudinal direction. Transverse properties are generally lower. A number of standard extrusion dies are available. Rolled product is available in a thickness range of 0.063” to 0.313” × 25” (0.16 to 0.795 cm × 63.5 cm) length times width dependent on gauge. Mechanical properties for HIP’d, extruded, and/or rolled AlBe metal matrix composites are in the annealed condition.

Physical properties

*High modulus-to-density ratio, 3.8 times that of aluminium or steel, minimizes flexure and reduces the chance of mechanically induced failure. *

Thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...

of approximately 210 W/m⋅K exceeds by about 25% that of common aluminium metal matrix composites such as Al 6061. *Polished AlBeMet exhibits significant surface scatter inherent in the composite structure and cannot be eliminated by optical polishing. (Typical surface roughness from an AlBeMet polished surface is in the 200–250 Å finish.) An amorphous coating such as electroless nickel is required. Surfaces in the 15 to 20 Å level are achievable. Depending on the CTE of the substrate material, a potential penalty of bi-metallic effect (bending forces?) between substrate and nickel surface finish is possible. With the tailoring of electroless nickel, this material dictates that the phosphorus content in the plating bath be approximately 11% to insure a CTE match close to that of the AlBeMet thereby eliminating any bi-metallic effect.

Fatigue properties

The fatigue properties of AlBeMet extruded material have been tested using the Krause rotating beam fatigue test utilizing fully reversed cycles with a R = +0.1. The

fatigue limit The fatigue limit or endurance limit is the stress level below which an infinite number of loading cycles can be applied to a material without causing fatigue failure. Some metals such as ferrous alloys and titanium alloys have a distinct limit, ...

, 1 × 10⁷ cycles was about 207 MPa (30 ksi) in the longitudinal direction and 165 MPa (25 ksi) in the transverse direction. This property is approximately 75% of the minimum RT yield strength, which is two times that of typical fatigue properties of 6061-T6 aluminium.

Manufacture of AlBeMet components

AlBeMet parts can be manufactured with the same techniques normally used for aluminium, meaning that special tools do not need to be developed. Although the material is safe to handle when not being worked on, the carcinogenic properties mean that special precautions must be taken to avoid exposure during machining with respiratory protection needed where dust could be formed.

References