All elements are dissolved in the copper rod, causing lattice distortion of the brass rod, causing wave scattering when free electrons flow in a directional way, and increasing resistivity. On the contrary, there is no solid solution element or few solid solution element in brass rod, and the influence of brass rod on the conductivity and thermal conductivity is very small. It should be noted that the solid solubility of some elements in the introductory copper bar of brass row decreases sharply with decreasing temperature and precipitates in the form of simple substances and metallic compounds. It can not only strengthen the copper rod alloy through solution and dispersion, but also reduce the conductivity very little, which is an important alloying principle in the study of high strength and high conductivity alloys. It should be noted that an alloy of iron, silicon, chromium and copper rods is an extremely important alloy of high strength and high conductivity. Cobalt-chromium-zirconium alloy is a well-known alloy with high strength and high conductivity because of the superimposed effects of alloying elements on the properties of copper rods.

2. The microstructure of copper-base corrosion resistant alloy should be single-phase to avoid electrochemical corrosion caused by the alloy. Single-phase brass rod, bronze rod and white copper rod used in engineering have excellent corrosion resistance and are important heat exchange materials.

3. There are both soft and hard phases in the microstructure of copper - based wear-resistant alloys. Therefore, it is necessary to ensure that the brass rod precipitates the hard phase in addition to the solid solution of the element added to the copper rod. The typical hard phases in copper bar alloys are Ni3Si and FeALSi compounds. In the tooth alloys of automobile synchronizer developed in recent years, the phase is soft phase, the negative phase is hard phase, and the phase should not exceed 10%.

4. Solid polycrystalline copper bar alloys have damping properties, such as copper manganese alloys, and solid thermoelastic martensitic alloys have memory properties, such as copper, zinc, aluminum and copper, aluminum and manganese alloys.

5. The color of the copper rod can be changed by adding alloying elements, such as zinc, aluminum, tin, nickel and so on. As the content changes, the color changes from red to green, and from yellow to white. If the content control is reasonable, imitation gold material and imitation silver alloy can be obtained.

6. The elements used in the alloying of brass rods and alloys should be common and inexpensive. Elements should be added based on the principle of diversity and small amounts. Alloy raw materials can be used comprehensively. The alloy should have excellent technological properties and be suitable for processing into various finished products and semi-finished products. With the continuous development of production and science and technology, there are many kinds of metal welding methods at present, if according to the characteristics of the welding process, it can be summarized into three categories: (classification family method) fusion welding, pressure welding, brazing.