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→5.1.6.1 Copper-Beryllium Alloys (Beryllium Bronze)
The cause for precipitation hardening of CuBe materials is the rapidly diminishing solubility of beryllium in copper as temperature decrease. As the
phase diagram for CuBe shows, 2.4 wt% of Be are soluble in Cu at 780°C <xr id="fig:Phase diagram of copperberyllium with temperature ranges for brazing and annealing treatments"/> (Fig. 5.28). In this temperature range annealed CuBe alloys are homogeneous(solution annealing). The homogeneous state can be frozen through rapid cooling to room temperature (quenching). Through a subsequent annealing at 325°C the desired precipitation hardening is achieved which results in a significant increase in mechanical strength and electrical conductivity of CuBe ''<xr id="tab:tab5.17"/> (Table Tab. 5.17)''. The final strength and hardness values depend on the annealing temperature and time as well as on the initial degree of cold working ''<xr id="tab:tab5.18"/> (Table 5.18)'' and [[#figures7|(Figs. 43 – 75)]](Figs. 5.29 - 5.31).
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<figtable id="tab:tab5.17">'''Table 5.17: Physical Properties of Selected Copper-Beryllium Alloys''' {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material<br />Designation<br />EN UNS !Composition<br />[wt%]!Density<br />[g/cm<sup>3</sup>]!colspan="2" style="text-align:center"|Electrical<br />Conductivity<br />[MS/m] [% IACS] !Electrical<br />Resistivity<br />[μΩ·cm]!Thermal<br />Conductivity<br />[W/(m·K)]!Coeff. of Linear<br />Thermal<br />Expansion<br />[10<sup>-6</sup>/K]!Modulus of<br />Elasticity<br />[GPa]!Softening Temperature<br />(approx. 10% loss in<br />strength)<br />[°C]!Melting<br />Temp Range<br />[°C]|-|CuNi25<br />CW350H<br />C71300|Ni 24 - 26<br />Mn 0.5<br />Zn 0.5<br />Fe 0.3<br />Cu Rest|8.94|3.0|5.2|33.3|29|15.5|147|ca. 500|1150 - 1210|-|CuNi9Sn2<br />CW351H<br />C72500|Ni 8.5 - 10.5<br />Sn 1.8 - 2.8<br />Mn 0.3<br />Fe 0.3<br />Cu Rest|8.89|6.4|11|15.6|50|16.5|140|ca. 480|1060 - 1120|-|CuNi10Fe1Mn<br />CW352H<br />C70600|Ni 9.0 - 11.0<br />Fe 1.0 - 2.0<br />Mn 0.5 - 1.0<br />Zn 0.5<br />Cu Rest|8.92|5.6|9|17.9|50|16.5|134|||-|CuNi30Mn1Fe<br />CW354H<br />C71500|Ni 30 - 32<br />Mn 0.5 - 1.5<br />Fe 0.4 - 1.0<br />Zn 0.5<br />Cu Rest|8.93|2.6|4|38.5|29|15.5|152||1180 - 1240|}</figtable> <figtable id="tab:tab5.18">'''Table 5.18: Mechanical Properties of Selected Copper-Beryllium Alloys''' ( {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material!Hardness<br />Condition!Tensile Strength R<sub>m</sub><br />[MPa]!0,2 Teile% Yield Strength<br />R<sub>p02</sub><br />[MPa]!Elongation<br />A<sub>50</sub><br />[%]!Vickers<br />Hardness<br />HV!Bend Radius<sup>1)</sup><br />perpendicular to<br />rolling direction!Bend Radius<sup>1)</sup><br />parallel to<br />rolling direction!Spring Bending<br />Limit σ<sub>FB</sub><br />[MPa]!Spring Fatigue<br />Limit σ<sub>BW</sub><br />[MPa]|-|CuNi25|R 290|≥ 290|100|30|70 - 100|||||-|CuNi9Sn2|R 340<br />R 380<br />R 450<br />R 500<br />R 560|340 - 410<br />380 - 470<br />450 - 530<br />500 - 580<br />560 - 650|≤ 250<br />≥ 200<br />≥ 370<br />≥ 450<br />≥ 520|20<br />8<br />4<br />2|75 - 110<br />100 - 150<br />140 - 170<br />160 - 190<br />180 - 210|0 x t<br />0 x t<br />0 x t<br />1 x t|0 x t<br />0 x t<br />0 x t<br />2 x t|520|250|-|CuNi10Fe1Mn|R 300<br />R 320|≥ 300<br />≥ 320|≤ 100<br />≤ 200|20|70 - 120<br />≥ 100|||||-|CuNi30Mn1Fe|R 350<br />R 410|350 - 420<br />≥ 410|≤ 120<br />≤ 300|35|80 - 120<br />≥ 110|||||}</figtable><sup>1)</sup> t: Strip thickness max. 0.5 mm
====5.1.6.2 Other Precipitation Hardening Copper Alloys====
