Resources: Standards & Properties - Copper & Copper Alloy Microstructures: Copper Beryllium

Overview

Copper beryllium alloys are used for their high strength and good electrical and thermal conductivities. There are two groups of copper beryllium alloys, high strength alloys and high conductivity alloys.

The wrought high strength alloys contain 1.6 to 2.0% beryllium and approximately 0.3% cobalt. The cast, high-strength alloys have beryllium concentrations up to 2.7%. The high conductivity alloys contain 0.2-0.7% beryllium and higher amounts of nickel and cobalt. These alloys are used in applications such as electronic connector contacts, electrical equipment such as switch and relay blades, control bearings, housings for magnetic sensing devices, non sparking applications, small springs, high speed plastic molds and resistance welding systems. Cast beryllium coppers are frequently used for plastic injection molds. The cast materials have high fluidity and can reproduce fine details in master patterns. Their high conductivity enables high production speed, while their good corrosion and oxidation resistance promotes long die life. The UNS designations for the wrought alloys are C17200 through C17400 and the cast alloys are C82000 through C82800.

The high strength of the copper beryllium alloys is attained by age hardening or precipitation hardening. The age or precipitation hardening results from the precipitation of a beryllium containing phase from a supersaturated solid solution of mostly pure copper. The precipitation occurs during the slow cooling of the alloys because the solubility of beryllium in alpha copper decreases with decreasing temperature. Typically the alloys are rapidly cooled from the annealing treatment, so the beryllium remains in solid solution with the copper. Then the alloy is given a precipitation or age hardening treatment for an hour or more at a temperature between 200 and 460 C. Upon tempering, the beryllium containing phases, called beryllides, precipitate out of solution.

During the first stage of precipitation, there is the homogeneous nucleation of Guinier-Preston (G-P) zones. The G-P zones are small precipitation domains in a supersaturated alpha copper solid solution. The G-P zones have no well defined crystal structure of their own and they contain a high concentration of, in this case, beryllium atoms. The formation of G-P zones usually coincides with a change in properties. In the case of beryllium copper alloys, the property change is an increase in strength. As age hardening progresses, coherent metastable gamma double prime precipitates form from the G-P zones. Followed by the precipitation of gamma prime precipitates. The strength of these alloys increases as a result of the coherency strains that develop at the interface between the matrix and the growing precipitates. Over aging of the copper beryllium alloys is avoided because the equilibrium gamma phase forms and causes a decreases in strength. The precipitation of the equilibrium gamma phase depletes the metastable gamma prime precipitates, and softens the alloys.

The cast copper beryllium alloys have the typical dendritic structure of alpha (pure) copper, with the addition of the beryllide phases. The general microstructural features of the beryllide phases are similar in the cast and wrought materials. The beryllides can be seen in the as polished condition, it is not necessary to etch the specimens to reveal their structure. Primary beryllides form blue gray intermetallic particles that can be up to 10 microns long. These beryllides form during solidification and have a Chinese script morphology. The secondary beryllides form after solidification and have a rod like morphology. In the high-strength alloy castings the inter dendritic network is composed of alpha and gamma. The gamma double prime and gamma prime precipitates, in both the high conductivity and high strength copper beryllium alloys, are too small to be resolved with an optical microscope, and therefore do not appear in the optical micrographs. The presence of the age hardening precipitates in the high strength alloys can be detected indirectly by the striations that appear through the grains. The striations result from the overlap of coherency strains at the interfaces between the precipitates and the matrix. There are striations on the polished surface of these alloys when the age hardening precipitates are present and the striations etch very dark. This dark etching is not seen in the high conductivity alloys, the aged and unaged microstructure appear very similar. The equilibrium gamma phase appears as dark nodules on a bright matrix in over aged copper beryllium alloys. These gamma precipitates are typically found at the grain boundaries and have a plate like morphology.

The microstructure of the wrought material, after precipitation hardening, contains roughly equiaxed, twinned grains of alpha copper and a dispersion of nickel, cobalt or nickel and cobalt beryllide particles. The grain sizes are relatively fine due the dispersion of the beryllides. The beryllide particles are roughly spherical and blue gray in color. The beryllides are finer in the wrought material than the cast material because they are broken up during the thermomechanical processing. There is no transformed beta in microstructure of the wrought materials because it is dissolved during thermomechanical processing. The gamma double prime and gamma prime precipitates responsible for the age hardening are too small to be resolved directly with an optical microscope. Etching the sample reveals the dark striations associated with the age hardened precipitates.

NOTE: The file size of the Larger and Largest View of the Micrographs are substantially larger than the thumbnail shown. The Larger View images range in size from 11K to 120K depending on the image. The Largest View images range in size from 125K to almost 500K.

Nominal Composition: Cu 99.5, Be 1.6-1.79 Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High copper alloys
	Product Form:
	Processing:	As cast
	Etchant:
	Scale Line Length:	~ 500Microns
	Alloy:	C17000
	Temper:
	Material:	Beryllium copper
	Source:	University of Florida

Nominal Composition: Cu 99.5, Be 1.6-1.79 Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High copper alloys
	Product Form:
	Processing:	As cast
	Etchant:
	Scale Line Length:	~ 50Microns
	Alloy:	C17000
	Temper:
	Material:	Beryllium copper
	Source:	University of Florida

Nominal Composition: Cu 99.5, Be 1.6-1.79 Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High copper alloys
	Product Form:
	Processing:	As cast
	Etchant:
	Scale Line Length:	~ 125Microns
	Alloy:	C17000
	Temper:
	Material:	Beryllium copper
	Source:	University of Florida

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 790 C (1450 F) and cold rolled 37% to full hard temper. Longitudinal section shows elongated grains of alpha phase and cobalt beryllides. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and cold rolled 37% to Hard temper
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208(arnmonium persulfate), 2.5% in distilled water
	Alloy:	C17200
	Temper:	TD04
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Cast, homogenized and hot worked. The microstructure shows nonuniform distribution of grain sizes, typical of hot worked product. Greater uniformity in grain size distribution may be achieved in the finished product by successive cold working and annealing operations. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Plate
	Processing:	Cast, homogenized and hot worked
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water
	Alloy:	C17200
	Temper:	M20 (Hot worked)
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 790 C (1450 F), quenched to room temperature. Longitudinal section shows equiaxed grains of supersaturated alpha phase, solid solution of beryllium in copper. Cobalt beryllide particles which do not dissolve during solution annealing are observed. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, and solution annealed
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208(anmonium persulfate), 2.5% in distilled water.
	Alloy:	C17200
	Temper:	TB00
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 790 C (1450 F), subsequently precipitation hardened at 315 C (600 F) for 3 h to achieve maximum attainable hardness. Longitudinal section shows equiaxed alpha grains and the cobalt beryllide phase uniformly dispersed throughout the matrix. The strengthening precipitates which result from precipitation heat treatment are not resolved by optical microscopy. Small amounts of equilibrium gamma phase are present in the grain boundaries. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and age hardened to maximum hardness
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water
	Alloy:	C17200
	Temper:	TF00
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Mill hardened to TMOO temper to achieve maximum formability at moderate strength. Longitudinal section shows roughly equiaxed grains of alpha copper-rich solid solution matrix phase. Small cobalt beryllide particles are uniformly dispersed throughout the matrix. Strengthening precipitates which form during precipitation heat treatment are not resolved by optical microscopy. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and mill hardened to specific property ranges
	Etchant:	Ammonium persulfate/anmonium hydroxide, 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water
	Alloy:	C17200
	Temper:	TM00
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 790 C (1450 F), precipitation heat treated at 370 C (700 F) for 6 h to attain the soft overaged condition. The structure shows equiaxed grains of alpha phase and equilibrium gamma precipitates in the grain boundaries, which appear as dark nodules in a light matrix. Striations in alpha matrix are the result of concurrent metastable precipitate formation, not optically resolvable. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, age hardened beyond the maximum hardness condition
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water
	Alloy:	C17200
	Temper:	Overaged
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Solution annealed, cold rolled 37% to Hard temper and precipitation hardened at 315 C (600 F) for 2 h to achieve maximum hardness. Longitudinal section shows elongated grains of alpha phase and cobalt beryllides. Striations are caused by metastable precipitates, not resolved by optical microscopy. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, cold rolled 37% to Hard temper, age hardened to maximum hardness
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water
	Alloy:	C17200
	Temper:	TH04
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Ph 0.02 max, Cu + Sum of Named Elements 99.5 min Description: Mill hardened to TM08 temper for high strength and limited formability. Longitudinal section shows the alpha copper-rich solid solution phase with elongated grains as a result of cold working before precipitation hardening. Cobalt beryllide particles are observed uniformly dispersed throughout the matrix. Striations are caused by metastable precipitation within the alloy. The strengthening precipitates which form during precipitation heat treatment are not resolved by optical microscopy. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, rolled and mill hardened to specific property ranges
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water
	Alloy:	C17200
	Temper:	TM08
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 0.4-0.7, Co 2.4-2.7, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 900 C (1650 F), and precipitation hardened at 480 C (900 F) for 3 h to achieve maximum hardness. Equiaxed fine grains of alpha phase are observed with small cobalt beryllide particles uniformly distributed throughout the matrix. The strengthening metastable precipitates are not resolved. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, and age hardened to maximum hardness
	Etchant:	Cyanide; 1 g KCN (potassium cyanide) and 100 ml. distilled water
	Alloy:	C17500
	Temper:	TF00
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 0.4-0.7, Co 2.4-2.7, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 900 C (1650 F), cold rolled to Hard temper and precipitation hardened at 480 C (900 F) for 2 h to achieve maximum hardness. Structure consists of elongated fine grains of alpha phase and cobalt beryllide phase uniformly distributed throughout the matrix. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, cold rolled and age hardened to maximum hardness
	Etchant:	Cyanide; 1 g KCN (potassium cyanide) and 100 ml. distilled water
	Alloy:	C17500
	Temper:	TH04
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 0.2-0.6, Ni 1.4-2.2, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 900 C (1650 F), and precipitation hardened at 480 C (900 F) for 3 h to achieve maximum hardness. Equiaxed grains of alpha phase are observed with small nickel beryllide particles uniformly distributed throughout the matrix. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and age hardened to maximum attainable hardness
	Etchant:	Cyanide; 1 g KCN (potassium cyanide) and 100 ml. distilled water
	Alloy:	C17510
	Temper:	TF00
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 0.2-0.6, Ni 1.4-2.2, Cu + Sum of Named Elements 99.5 min Description: Solution annealed at 900 C (I 650 F), cold rolled 11%, and precipitation hardened at 480 C (900 F) for 2 h to achieve maximum hardness. Structure consists of slightly elongated grains of alpha phase, and small nickel beryllide particles. The strengthening metastable precipitates are not resolved. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Strip
	Processing:	Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, cold rolled and age hardened to maximum hardness
	Etchant:	Cyanide / peroxide / hydroxide - 20 ml. KCN (potassium cyanide), 5 ml. H202 (hydrogen peroxide), and 1 to 2 ml. NH40H (ammonium hydroxide)
	Alloy:	C17510
	Temper:	TH01
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 0.60, Ni 1.5, Cu + Sum of Named Elements 99.5 min Description: As-cast microstructure showing interdendritic networks of large primary beryllide phase that form during solidification in an alpha copper-rich solid solution matrix. Small needle-like secondary beryllides with preferred crystallographic orientation, which precipitate from solid solution during slow cooling after casting, are observed throughout. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Casting
	Processing:	As-cast
	Etchant:	Cyanide - 1 g KCN (potassium cyanide) and 100 ml. distilled water
	Alloy:	C82200
	Temper:
	Material:	Beryllium Copper
	Source:	Materion Corporation

Nominal Composition: Be 2.06, Co 0.50, Si 0.25, Cu + Sum of Named Elements 99.5 min. Description: Cast, solution annealed at 790 C (1450 F) and aged to peak hardness (Rockwell C38-43), at 315 C (600 F) for 3 h. Microstructure shows script beryllides, and angular beta phase, transformed to a lamellar aggregate of alpha and gamma phases, in an alpha copper-rich solid solution matrix. Striations are the result of metastable precipitation in the alloy. Larger View of Micrograph Largest View of Micrograph	Alloy Family:	High Copper Alloys
	Product Form:	Casting
	Processing:	Cast, solution annealed and aged
	Etchant:	Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water
	Alloy:	C82500
	Temper:	TF00
	Material:	Beryllium Copper
	Source:	Materion Corporation

Beryllium Copper

Overview