1. CU-NI alloy with NI < 50% (wt) is called cupronickel. Copper and nickel are infinitely miscible because of their close proximity to each other in the periodic table, their similar electrochemical properties and atomic RADII, and their face centered cubic lattices. In Cu-Ni binary alloy, the Curie point decreases with the decrease of NI content. When the nickel content drops to 74% , the Curie point drops to room temperature, when the nickel content drops to 50% , the Curie point drops TO-200 °C. The strength, corrosion resistance, resistance and thermoelectricity of copper can be improved remarkably by adding nickel into copper. Copper-nickel alloys for industrial use are divided into structural cupronickel and electrical cupronickel according to their properties and uses. The copper-nickel Binary Alloy is called simple cupronickel. The outstanding feature of simple cupronickel is its high chemical stability in various corrosive media such as sea water, organic acids and various salt solutions, and its excellent cold and hot working properties. The "B" of the bronze number is indicated by the nickel content (%) added after it. White copper containing other elements is called complex white copper or special white copper. White copper containing MN is called manganese white copper, also known as Constantan, such as BMn40-1.5, its composition (wt) is containing 40% NI, containing 1.5% MN. The addition of a small amount of manganese or iron in cupronickel not only refines the grain size, but also improves the corrosion resistance of cupronickel. Therefore, iron-containing complex Cupronickel, BFe30-1-1 and BFe5-1, can be used as working parts in marine vessels and other strongly corrosive media. The main role of zinc in cu-ni alloy is solid solution strengthening and improving corrosion resistance. Zinc cupronickel contains Ni between 5% and 35% (WT) and Zn between 13% and 45% (WT) . Among them, BZn15-20 is the most widely used, with high corrosion resistance, good processability, beautiful silvery white color, small specific gravity and low cost. PB and trace selenium (Se) and tellurium (Te) with less than 2% (wt) can improve the processability of zinc white copper, suitable for manufacturing precision machine parts. The solubility of AL in cu-ni alloy decreases with the decrease of temperature and can be strengthened by solid solution. For example, the aluminum cupronickel Bal13-3 and BAl16-1.5 not only have excellent mechanical properties and corrosion resistance, but also have high elasticity and low temperature resistance. At 90K (- 183 °C) low temperature, the mechanical properties are not reduced, but improved! The addition of Ti (Ti) , Zr (Zr) , Ne (Niobium) and Mo to cu-ni alloy can improve the casting properties, room temperature mechanical properties and thermoplastic properties, as well as the welding and corrosion resistance. The mechanical properties and uses of Cupronickel for corrosion resistant structures are listed below:

B 5 Strip M, tensile strength 220MPA, elongation 32% strip Y, tensile strength 400MPA, elongation 10% for marine corrosion-resistant parts. B19 Strip Y, tensile strength 400MPA, elongation 10% strip M, tensile strength 300MPA, elongation 25% strip Y, tensile strength 400MPA, elongation 3% sheet M, tensile strength 300MPA, elongation 30% sheet y, tensile strength 400MPA, the elongation rate of 3% is used in the steam, freshwater river seawater in the work of precision instruments, instrument parts, Metal Mesh River anti-chemical corrosion parts. B30 Strip M, tensile strength 380MPa strip Y, tensile strength 550MPa plate M, tensile strength 380MPA, elongation 23% plate Y, tensile strength 550MPA, elongation 3% for corrosion resistant parts working in steam and sea water, the metal tube working under high temperature and high pressure can condense the tube. BMn3-12 strip M, tensile strength 360MPA, elongation 25% sheet Y, tensile strength 360MPA, elongation 25% for the same purpose. BZn15-20 strip M, tensile strength 350MPA, elongation 3.5% strip Y, tensile strength 550MPA, elongation 1.5% strip t, tensile strength 650MPA, Elongation 1% sheet M, tensile strength 350MPA, elongation 3.5% strip Y, tensile strength 550MPA, elongation 2% sheet t, tensile strength 650MPA, elongation 1% control bar Y, diameter 5-20mm, tensile strength 450MPA, elongation 5% control bar Y, diameter 21-30mm, tensile strength 400MPA, elongation 7% control bar Y, diameter 31-40mm, tensile strength 350MPA, elongation 12% control bar M, tensile strength 300MPA, elongation 30% for precision instrument parts, industrial utensils, medical machinery. BAl6-1.5 sheet, tensile strength 550MPA, elongation 3% for the manufacture of spring and elastic parts.

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B0.6 thermal conductivity 272 W/(m °C) resistivity 0.031106 m resistance temperature coefficient 0.0028/°C

Simple cupronickel B16 linear expansion coefficient 15.3106/°C resistivity 0.223106 m resistance temperature coefficient 0.0028/°C

Coefficient of linear expansion 14.4106/°c specific heat c 410j/kg °c thermal conductivity 21w/(m °C) resistivity 0.435106 m resistance temperature coefficient 0.00002/°c

The Coefficient of linear expansion of copper BMn43-0.5 is 14.4106/°C thermal conductivity 24 W/(m °C) resistivity 0.49106 m resistance temperature coefficient-0.00014/°c

3. Bal2-3 can be strengthened by heat treatment. After solution at 900 °C, cold rolling at 50% and aging at 550 °C, the strength of Bal2-3 can reach 800-1000MPa, and the solution state is only 250-350MPa. It is necessary to carry out homogenization annealing because of the serious in-crystal segregation of white copper ingot. B19, B30, temperature 100-1050 °C, time 3-4hBMn3-12, temperature 830-870 °C, time 2-3hBMn40-1.5, temperature 1050-1150 °C, time 3-4hBZn15-20, temperature 940-970 °C, different Heat treatment process of 2-3h Cupronickel has great influence on its performance. BMn3-12 used in precision instrument should be de-stress annealed to make the resistance stable. BMn40-1.5 working at high temperature should be annealed at 750-850 °C, water-cooled or air-cooled. Low temperature annealing at 325-375 °C can be used for the preparation of zinc white copper BZn15-20 for elastic elements. As the effective thickness (mm) decreases, the intermediate annealing temperature (c) of cupronickel machined parts needs to be appropriately reduced as follows:

B19、B25

750-780℃（＞5mm）   700-750℃（15-mm）

620-700℃（0.5-1mm）   530-620℃（＜0.5mm）

BZn15-20\bmN3-12

700-750℃（大于5mm）   680-730℃（1-5mm）

600-700℃（0.5-1mm）   520-600℃（＜0.5mm）

BAl6-1.5、BAl13-3

700-750℃（＞5mm）   700-730（1-5mm）

580-700℃（0.5-1mm）   550-600℃（＜0.5mm）

BMn40-1.5

800-850℃（＞5mm）   750-800℃（1-5mm）

600-750℃（0.5-1mm）   550-600℃（＜0.5mm）

The annealing temperature of white copper bar and wire varies with the different state of "semi-hard and soft" before annealing, as follows:

BZn15-20 BAR, semi-hard 400-420 °C, soft 650-700 °C wire 0.3-6.0, soft 650-700 °C BMn3-12 wire 0.3-6.0, soft 500-540 °c BMn40-1.5 wire 0.3-0.8, soft 670-680 °C wire 0.85-2.0, soft 690-700 °C wire 2.1-6.0, soft 710-730 °C 

SOURCE: Learn a little heat treatment every day