Changes

====5Besides the naturally hard copper materials, precipitation hardening copper alloys play also an important role as carrier materials for electrical contacts.1By means of a suitable heat treatment, finely dispersed precipitations of a second phase can be achieved, that increases the mechanical strength of these copper alloys significantly.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 thephase 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)1. In this temperature range annealed CuBe alloys are homogeneous(solution annealing)6. The homogeneous state can be frozen through rapid cooling to room temperature 1-->Copper-Beryllium Alloys (quenchingBeryllium Bronze). 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 ''(Table 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 ''(Table 5.18)'' and [[#figures7|(Figs. 43 – 75)]](Figs. 5.29 - 5.31).====

The cause for precipitation hardening of CuBe materials, is the rapidly diminishing solubility of beryllium in copper as temperature decreases. As thephase diagram for CuBe shows, 2.4 wt% of Be are soluble in Cu at 780°C (<figure xr id="fig:Phase diagram of copperberyllium with temperature ranges for brazing and annealing treatmentsPhase_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: Phase diagram of copperberyllium with Physical_Properties_of_Selected_Copper_Beryllium_Alloys"/><!--(Tab. 5.17)-->). The final strength and hardness values depend on the annealing temperature ranges for brazing and annealing treatments[[Filetime, as well as on the initial degree of cold working (<xr id="tab:Phase diagram Mechanical Properties of copper beryllium with temperature rangesSelected Copper-Beryllium Alloys"/><!--(Table 5.jpg|right|thumb|Phase diagram of copper18)-- beryllium with temperature ranges for brazing > and annealing treatments]]<xr id="fig:Precipitation_hardening_of_CuBe2_at_325°C_after_different_cold_working"/>, <xr id="fig:Precipitation_hardening_of_CuBe2_(soft)_at_325°C"/>, <xr id="fig:Precipitation_hardening_of_CuBe2_(half hard)_at_different_annealing_temperatures"/figure>).

Since Beryllium is rated as a carcinogen by the European regulation EU-67/548As precipitation hardening alloys CuBe materials, it has been tried to reach the application properties of the well established mainly CuBe2 and CuBe1.7 have gained broad usage as current carrying contact springs because of their outstanding mechanical properties. Besides these, CuCo2Be and CuNi2Be, which have medium mechanical strength and CuBe2 alloys with a lower Be contentrelatively high electricalconductivity, are also used as contact carrier materials. The development efforts for alternate After stamping and forming into desired contact configurations, these CuBe materials are then precipitation hardening hardened. CuBe alloys are available as semi-finished materials without toxic in a variety of cold work conditions. They can also be supplied and declaration requiring additive materialsused in the already precipitation hardened condition, for example CuNiCoSiwithout significant strength losses. In this case, are aimed the hardening was already performed at the replacement of CuBealloy producer.

<div id="figures7"><xr id="fig:Precipitation hardening Since Beryllium is rated as a carcinogen by the European regulation EU-67/548, it has been tried to reach the application properties of the well established CuBe1.7 and CuBe2 at 325°C after different cold working"/> Figalloys with a lower Be content. Development efforts for alternative precipitation hardening materials without toxic and declarable additives are underway, e.g. 5CuNiCoSi as a substitute for CuBe.29: Precipitation hardening of CuBe2 at 325°C after different cold working

<xr iddiv class="fig:Precipitation hardening of CuBe2 (soft) at 325°Cmultiple-images"/> Fig. 5.30: Precipitation hardening of CuBe2 (soft) at 325°C

<xr figure id="fig:Precipitation hardening of CuBe2 (half hard) at different annealing temperaturesPhase_diagram_of_copperberyllium_with_temperature_ranges_for_brazing_and_annealing_treatments"/> Fig[[File:Phase diagram of copper beryllium with temperature ranges. 5.31: Precipitation hardening jpg|left|thumb|<caption>Phase diagram of CuBe2 (half hard) at different copper- beryllium with temperature ranges for brazing and annealing temperaturestreatments</caption>]]</divfigure>

<div class="multiple-images"><figure id="fig:Precipitation hardening of CuBe2 at 325°C after different cold workingPrecipitation_hardening_of_CuBe2_at_325°C_after_different_cold_working"> [[File:Precipitation hardening of CuBe2 at 325C.jpg|rightleft|thumb|<caption>Precipitation hardening of CuBe2 at 325°C after different cold working</caption>]]

<figure id="fig:Precipitation hardening of CuBe2 Precipitation_hardening_of_CuBe2_(soft) at 325°C_at_325°C"> [[File:Precipitation hardening of CuBe2 (soft) at 325C.jpg|rightleft|thumb|<caption>Precipitation hardening of CuBe2 (soft) at 325°C</caption>]]

<figure id="fig:Precipitation hardening of CuBe2 Precipitation_hardening_of_CuBe2_(half hard) at different annealing temperatures_at_different_annealing_temperatures"> [[File:Precipitation hardening of CuBe2 half hard.jpg|rightleft|thumb|<caption>Precipitation hardening of CuBe2 (half hard) at different annealing temperatures</caption>]]

<figtable id="tab:Physical_Properties_of_Selected_Copper_Beryllium_Alloys"><caption>'''<!--Table 5.17:-->Physical Properties of Selected Copper-Beryllium Alloys'''</caption>  {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material<br />Designation<br />EN UNS !Composition<br />[wt%]!Density<br />[g/cm³]!colspan="2" style="text-align:center"|Electrical<br />Conductivity !Electrical<br />Resistivity<br />[μΩ·cm]!Thermal<br />Conductivity<br />[W/(m·K)]!Coeff. of Linear<br />Thermal<br />Expansion<br />[10^-6/K]!Modulus of<br />Elasticity<br />[GPa]!Softening Temperature<br />(approx. 10% loss in<br />strength)<br />[°C]!Melting<br />Temp Range<br />[°C]|-! !!![MS/m] ![% IACS]!!!!!!|-|CuBe1.7<br />CW100C<br />C17000|Be 1.6 - 1.8<br />Co 0.3<br />Ni 0.3<br />Cu Rest|8.4|8 - 9[[#text-reference1|^a]]<br />12 - 13[[#text-reference2|^b]]<br />11[[#text-reference3|^c]]|14 - 16<br />21 - 22<br />19|11 - 12.5[[#text-reference1|^a]]<br />7.7 - 8.3[[#text-reference2|^b]]9.1[[#text-reference3|^c]]|110|17|125[[#text-reference1|^a]]<br />[[#text-reference2|^b]]|ca. 380|890 - 1000|-|CuBe2<br />CW101C<br />C17200|Be 1.8 - 2.1<br />Co 0.3<br />Ni 0.3<br />Cu Rest|8.3|8 - 9[[#text-reference1|^a]]<br />12 - 13[[#text-reference2|^b]]<br />11[[#text-reference3|^c]]|14 - 16<br />21 - 22<br />19|11 - 12.5[[#text-reference1|^a]]<br />7.7 - 8.3[[#text-reference2|^b]]<br />9.1[[#text-reference3|^c]]|110|17|125[[#text-reference1|^a]]<br />135[[#text-reference2|^b]]|ca. 380|870 - 980|-|CuCo2Be<br />CW104C<br />C17500|Co 2.0 - 2.8<br />Be 0.4 - 0.7<br />Ni 0.3<br />Cu Rest|8.8|11 - 14[[#text-reference1|^a]]<br />25 - 27[[#text-reference2|^b]]<br />27 - 34[[#text-reference3|^c]]|19 - 24<br />43 - 47<br />47 - 59|7.1 - 9.1[[#text-reference1|^a]]<br />3.7 - 4.0[[#text-reference2|^b]]<br />2.9[[#text-reference3|^c]]|210|18|131[[#text-reference1|^a]]<br />138[[#text-reference2|^b]]|ca. 450|1030 - 1070|-|CuNi2Be<br />CW110C<br />C17510|Ni 1.4 - 2.2<br />Be 0.2 - 0.6<br />Co 0.3<br />Cu Rest|8.8|11 - 14[[#text-reference1|^a]]<br />25 - 27[[#text-reference2|^b]]<br />27 - 34[[#text-reference3|^c]]|19 - 24<br />43 - 47<br />47 - 59|7.1 - 9.1[[#text-reference1|^a]]<br />3.7 - 4.0[[#text-reference2|^b]]<br />2.9[[#text-reference3|^c]]|230|18|131[[#text-reference1|^a]]<br />138[[#text-reference2|^b]]|ca. 480|1060 - 1100|}<div id="text-reference1">_a solution annealed, and cold rolled</div><div id="text-reference2">_b solution annealed, cold rolled, and precipitation hardened</div><div id="text-reference3">_c solution annealed, cold rolled, and precipitation hardened at mill (mill hardened)</div></figtable><br/><br/> <figtable id="tab: Mechanical Properties of Selected Copper-Beryllium Alloys"><caption>''' (<!--Table 5.18:-->Mechanical Properties of Selected Copper-Beryllium Alloys'''</caption>  {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material!Hardness<br />Condition!Tensile Strength R_m<br />[MPa]!0,2 Teile% Yield Strength<br />R_p02<br />[MPa]!Elongation<br />A₅₀<br />[%]!Vickers<br />Hardness<br />HV!Bend Radius[[#text-reference4|¹]]<br />perpendicular to<br />rolling direction!Bend Radius[[#text-reference4|¹]]<br />parallel to<br />rolling direction!Spring Bending<br />Limit σ_FB<br />[MPa]!Spring Fatigue<br />Limit σ_BW<br />[MPa]|-|CuBe1,7|R 390[[#text-reference5|^a]]<br />R 680[[#text-reference5|^a]]<br />R 1030[[#text-reference6|^b]]<br />R 1240[[#text-reference6|^b]]<br />R 680[[#text-reference7|^c]]<br />R 1100[[#text-reference7|^c]]|380 -520<br />680 - 820<br />1030 - 1240<br />1240 - 1380<br />680 - 750<br />1100 - 1200|&ge; 180<br />&ge; 600<br />&ge; 900<br />&ge; 1070<br />&ge; 480<br />&ge; 930|35<br />2<br />3<br />1<br />18<br />3|80 - 135<br />210 - 250<br />330 - 380<br />360 - 420<br />220 - 350<br />330 - 370|0 x t<br />1 x t<br />1 x t<br /><br />1 x t<br />6 x t|0 x t<br />3 x t<br />1.5 x t<br /><br />1 x t<br />10 x t| <br /> <br />700<br />1000<br />390<br />790| <br /> <br />260<br />280<br /> <br />260|-|CuBe2|R 410[[#text-reference5|^a]]<br />R 690[[#text-reference5|^a]]<br />R 1140[[#text-reference6|^b]]<br />R 1310[[#text-reference6|^b]]<br />R 690[[#text-reference7|^c]]<br />R 1200[[#text-reference7|^c]]|410 -540<br />690 - 820<br />1140 - 1310<br />1310 - 1480<br />690 - 760<br />1200 - 1320|&ge; 190<br />&ge; 650<br />&ge; 1000<br />&ge; 1150<br />&ge; 480<br />&ge; 1030|35<br />2<br />3<br />1<br />18<br />3|90 - 140<br />215 - 260<br />350 - 400<br />380 - 450<br />220 - 250<br />360 - 410|0 x t<br />1 x t<br /> <br /> <br />1 x t<br />5 x t|0 x t<br />3 x t<br /> <br /> <br />1.5 x t<br />10 x t| <br /> <br />800<br />1040<br />400<br />900| <br /> <br />270<br />300<br /> <br />280|-|CuCo2Be<br />CuNi2Be|R 250[[#text-reference5|^a]]<br />R 550[[#text-reference5|^a]]<br />R 650[[#text-reference6|^b]]<br />R 850[[#text-reference6|^b]]<br />R 520[[#text-reference7|^c]]|250 - 380<br />550 - 700<br />650 - 820<br />850 - 1000<br />520 - 620|&ge; 140<br />&ge; 450<br />&ge; 520<br />&ge; 750<br />&ge; 340|20<br />2<br />10<br />1<br />5|60 - 90<br />160 - 200<br />195 - 230<br />240 - 290<br />150 - 180|0 x t<br />3 x t<br />1 x t<br />3 x t<br />1 x t|0 x t<br /> <br />1 x t<br />3.5 x t<br />1 x t| <br /> <br />360<br />650<br />300| <br /> <br />220<br />250<br />210|}<div id="text-reference4">₁ t: Strip thickness max. 0.5 mm</div><div id="text-reference5">_a solution annealed, and cold rolled</div><div id="text-reference6">_b solution annealed, cold rolled, and precipitation hardened</div><div id="text-reference7">_c solution annealed, cold rolled, and precipitation hardened at mill (mill hardened)</div></figtable> <br/><br/> ====<!--5.1.6.2-->Other Precipitation Hardening Copper Alloys====

=====<!--5.1.6.2 Other Precipitation Hardening .1-->Copper -Chromium Alloys=====

As the phase diagram shows, copper-chromium has a similar hardening profile compared to CuBe (<xr id====="fig:Copper corner of the copper-chromium phase diagram for up to 0.8 wt% chromium"/><!--(Fig. 5.132)-->). In the hardened stage CuCr has limitations to work hardening. Compared to copper it has a better temperature stability with good electrical conductivity. Hardness and electrical conductivity as a function of cold working and precipitation hardening conditions are illustrated in [[#figures8|(Figs.6– 9]]<!--Figs.25.1 33-5.35--> and <xr id="tab:Physical Properties of Other Precipitation Hardening CopperAlloys"/><!--(Tables 5.19)-Chromium -> and <xr id="tab:Mechanical Properties of Other Precipitation Hardening Copper Alloys====="/><!--(Tab. 5.20)-->).

As the phase diagram shows, copper-chromium has a similar hardening profile compared to CuBe <xr id="fig:Copper corner of the copper-chromium phase diagram materials are especially suitable for up to 0.8 wt% chromium"/>(Fig. 5use as electrodes for resistance welding.32). In During brazing the hardened stage CuCr has limitations to work hardening. Compared to copper it has a better temperature stability with good electrical conductivity. Hardness loss in hardness is limited, if low melting brazing alloys and electrical conductivity as a function of cold working and precipitation hardening conditions reasonably short heating times are illustrated in Figs. 5.33-5.35 ''(Tables 5.19 and 5.20)''used.

Copper<div class="multiple-chromium materials are especially suitable for use as electrodes for resistance welding. During brazing the loss in hardness is limited if low melting brazing alloys and reasonably short heating times are used.images">

Fig. 5.32: Copper corner of the copper-chromium phase diagram for up to 0.8 wt% chromium[[File:Copper corner of the copper chromium phase diagram.jpg|rightleft|thumb|<caption>Copper corner of the copper-chromium phase diagram for up to 0.8 wt% chromium</caption>]] </figure> <figure id="fig:Softening of precipitation hardened and subsequently cold worked CuCr1"> [[File:Softening of precipitation hardened and subsequently cold worked CuCr1.jpg|left|thumb|<caption>Softening of precipitation-hardened and subsequently cold worked CuCr1 after 4hrs annealing</caption>]]</figure> <figure id="fig:Electrical conductivity of precipitation hardened CuCr 0.6"> [[File:Electrical conductivity of precipitation hardened CuCr 0.6.jpg|left|thumb|<caption>Electrical conductivity of precipitation hardened CuCr 0.6 as a function of annealing conditions</caption>]]

Fig. 5.33<figure id="fig: Softening Hardness of precipitation-hardened and subsequently cold worked CuCr1 after 4hrs annealingCuCr 0.6"> [[File:Softening Hardness of precipitation hardened and subsequently cold worked CuCr1CuCr 0.6.jpg|rightleft|thumb|Softening <caption>Hardness of precipitation-hardened and subsequently cold worked CuCr1 after 4hrs CuCr 0.6 as a function of annealingconditions</caption>]]</figure>

Fig. 5.34 a<figure id="fig: Electrical conductivity and hardness of precipitation hardened CuCr 0.6 as a function of annealing conditions"> [[File:Electrical conductivity and hardness of precipitation hardened CuCr 0.6.jpg|rightleft|thumb|<caption>Electrical conductivity and hardness of precipitation hardened CuCr 0.6 as a function of annealing conditionsafter cold working</caption>]]</figure></div><div class="clear"></div>

Fig. 5.35<figtable id="tab: Electrical conductivity and hardness Physical Properties of precipitation hardened CuCr 0Other Precipitation Hardening Copper Alloys"><caption>'''<!--Table 5.6 after cold working[[File19:Electrical conductivity and hardness -->Physical Properties of precipitation hardened CuCr 0.6.jpg|right|thumb|Electrical conductivity and hardness of precipitation hardened CuCr 0.6 after cold working]]Other Precipitation Hardening Copper Alloys'''</caption>

'''Table 5{| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material<br />Designation<br />EN UNS !Composition<br />[wt%]!Density<br />[g/cm³]!colspan="2" style="text-align:center"|Electrical<br />Conductivity !Electrical<br />Resistivity<br />[μΩ·cm]!Thermal<br />Conductivity<br />[W/(m·K)]!Coeff.19: Physical Properties of Other Precipitation Hardening Copper Alloys''' Linear<br />Thermal<br />Expansion<br />[10^-6/K]!Modulus of<br />Elasticity<br />[GPa]!Softening Temperature<br />(approx. 10% loss in<br />strength)<br />[°C]!Melting<br />Temp Range<br />[°C]|-!!!![MS/m] ![% IACS]!!!!!!|-|CuCr|Cr 0.3 - 1.2<br />Cu Rest|8.89|26[[#text-reference8|^a]]<br />48[[#text-reference9|^b]]|45[[#text-reference8|^a]]<br />83[[#text-reference9|^b]]|3.8[[#text-reference8|^a]]<br />2.1[[#text-reference9|^b]]|170[[#text-reference8|^a]]<br />315[[#text-reference9|^b]]|17|112|ca. 450|980 - 1080|-|CuZr|Zr 0.1 - 0.3<br />Cu Rest|8.9|35[[#text-reference8|^a]]<br />52[[#text-reference9|^b]]|60[[#text-reference8|^a]]<br />90[[#text-reference9|^b]]|2.9[[#text-reference8|^a]]<br />1.9[[#text-reference9|^b]]|340[[#text-reference8|^a]]|16|135|ca. 500|1020 - 1080|-|CuCr1Zr<br />CW106C<br />C18150|Cr 0.5 - 1.2 Teile!)<br />Zr 0.03 - 0.3<br />Cu Rest|8.92|20[[#text-reference8|^a]]<br />43[[#text-reference9|^b]]|34[[#text-reference8|^a]]<br />74[[#text-reference9|^b]]|5.0[[#text-reference8|^a]]<br />2.3[[#text-reference9|^b]]|170[[#text-reference8|^a]]<br />310 - 330[[#text-reference9|^b]]|16|110[[#text-reference8|^a]]<br />130[[#text-reference9|^b]]|ca. 500|1070 - 1080|}<div id="text-reference8">_a solution annealed, and cold rolled</div><div id="text-reference9">_b solution annealed, cold rolled, and precipitation hardened</div></figtable><br /><br />

<figtable id="tab:Mechanical Properties of Other Precipitation Hardening Copper Alloys"><caption>'''<!--Table 5.20: -->Mechanical Properties of Other Precipitation Hardening Copper Alloys'''</caption>

<table borderclass="1" cellspacing="0" style="border-collapse:collapsetwocolortable"><tr><tdth><p class="s16">Material</p></tdth><tdth><p class="s16">Hardness</p><p class="s16">Condi- tion</p></tdth><tdth><p class="s16">Tensile</p><p class="s16">Strength R<span class="s18">m</span></p><p class="s16">[MPa]</p></tdth><tdth><p class="s16">0,2% Yield</p><p class="s16">Strength R<span class="s18">p02</span></p><p class="s16">[MPa]</p></tdth><tdth><p class="s16">Elongation</p><p class="s16">A50</p><p class="s16">[%]</p></tdth><tdth><p class="s16">Vickers</p><p class="s16">Hardness</p><p class="s16">HV</p></tdth><tdth><p class="s16">Spring Bending</p><p class="s16">Limit <span class="s19">F</span><span class="s18">FB </span>[MPa]</p></tdth></tr><tr><td><p class="s16">CuCr</p></td><td><p class="s16">R 230<span class="s18">a</span></p><p class="s16">R 400<span class="s18">a </span>R 450<span class="s18">b </span>R 550<span class="s18">b</span></p></td><td><p class="s33">&gt;<span class="s16"> 230</span></p><p class="s33">&gt;<span class="s16"> 400</span></p><p class="s33">&gt;<span class="s16"> 450</span></p><p class="s33">&gt;<span class="s16"> 550</span></p></td><td><p class="s33">&gt;<span class="s16"> 80</span></p><p class="s33">&gt;<span class="s16"> 295</span></p><p class="s33">&gt;<span class="s16"> 325</span></p><p class="s33">&gt;<span class="s16"> 440</span></p></td><td><p class="s16">30</p><p class="s16">10</p><p class="s16">10</p><p class="s16">8</p></td><td><p class="s33">&gt;<span class="s16"> 55</span></p><p class="s33">&gt;<span class="s16"> 120</span></p><p class="s33">&gt;<span class="s16"> 130</span></p><p class="s33">&gt;<span class="s16"> 150</span></p></td><td><p class="s16">350</p></td></tr><tr><td><p class="s16">CuZr</p></td><td><p class="s16">R 260<span class="s18">a</span></p><p class="s16">R 370<span class="s18">a </span>R 400<span class="s18">b </span>R 420<span class="s18">b</span></p></td><td><p class="s33">&gt;<span class="s16"> 260</span></p><p class="s33">&gt;<span class="s16"> 370</span></p><p class="s33">&gt;<span class="s16"> 400</span></p><p class="s33">&gt;<span class="s16"> 420</span></p></td><td><p class="s33">&gt;<span class="s16"> 100</span></p><p class="s33">&gt;<span class="s16"> 270</span></p><p class="s33">&gt;<span class="s16"> 280</span></p><p class="s33">&gt;<span class="s16"> 400</span></p></td><td><p class="s16">35</p><p class="s16">12</p><p class="s16">12</p><p class="s16">10</p></td><td><p class="s33">&gt;<span class="s16"> 55</span></p><p class="s33">&gt;<span class="s16"> 100</span></p><p class="s33">&gt;<span class="s16"> 105</span></p><p class="s33">&gt;<span class="s16"> 115</span></p></td><td><p class="s16">280</p></td></tr><tr><td><p class="s16">CuCr1Zr</p></td><td><p class="s16">R 200<span class="s18">a</span></p><p class="s16">R 400<span class="s18">b</span></p><p class="s16">R 450<span class="s18">b</span></p></td><td><p class="s33">&gt;<span class="s16"> 200</span></p><p class="s33">&gt;<span class="s16"> 400</span></p><p class="s33">&gt;<span class="s16"> 450</span></p></td><td><p class="s33">&gt;<span class="s16"> 60</span></p><p class="s33">&gt;<span class="s16"> 210</span></p><p class="s33">&gt;<span class="s16"> 360</span></p></td><td><p class="s16">30</p><p class="s16">12</p><p class="s16">10</p></td><td><p class="s33">&gt;<span class="s16"> 70</span></p><p class="s33">&gt;<span class="s16"> 140</span></p><p class="s33">&gt;<span class="s16"> 155</span></p></td><td><p class="s16">420</p></td></tr></table></figtable>

=====<!--5.1.6.2.2 -->Copper-Zirconium Alloys=====

The solubility of Zirconium in copper is 0.15 wt% Zr at the eutectic temperature of 980°C ''(<xr id="fig:Copper corner of the copper zirconium for up to 0.5-wt zirconium"/><!--(Fig. 5.36)''-->). Copper-zirconium materials have a similar properties spectrum , compared to the one for copper-chromium materials. At room temperature the mechanical properties of copper-zirconium are less suitable than those of copper chromium, its temperature stability is however at least the same.

=====<!--5.1.6.2.3 -->Copper-Chromium-Zirconium Alloys=====

The earlier used CuCr and CuZr materials have been partially replaced over the years , by the capitation hardening three materials alloy CuCr1Zr. This material exhibits high mechanical strength at elevated temperatures and good oxidation resistance as well as high softening temperatures. In its hardened condition CuCr1Zr has also a high electrical conductivity (<xr id="fig:Softening of CuCr1Zr after 1hr annealing"/><!--(Bild 5.37)-->). Their usage extends from mechanically and thermally highly stressed parts , such as contact tulips in high voltage switchgear to or electrodes for resistance welding.

Fig. 5.36<div class="multiple-images"><figure id="fig: Copper corner of the copperzirconium copper zirconium for up to 0.5 -wt% zirconium">[[File:Copper corner of the copper zirconium for up to 0.5-wt zirconium.jpg|right|thumb|Figure 10: Copper corner of the copper- zirconium for up to 0.5 wt% zirconium]] </figure>

Fig. 5.37<figure id="fig: Softening of CuCr1Zr after 1 hr 1hr annealing and after 90% cold working">[[File:Softening of CuCr1Zr after 1hr annealing.jpg|right|thumb|Figure 11: Softening of CuCr1Zr after 1 hr annealing and after 90% cold working]]</figure></div><div class="clear"></div>