Physical and mechanical properties of die-cast copper alloys
As an important engineering material, die-cast copper alloys’ physical and mechanical properties are key indicators of their application value and are of great concern in industrial production. Physical properties primarily include density, melting point, thermal conductivity, electrical conductivity, and coefficient of thermal expansion, while mechanical properties encompass tensile strength, yield strength, elongation, hardness, and impact toughness. These interrelated properties collectively determine the applicability of die-cast copper alloys under different operating conditions. For example, in the electronics and electrical field, copper alloys require excellent electrical and thermal conductivity; in the mechanical manufacturing field, higher requirements are placed on their mechanical properties. In-depth research and understanding of the physical and mechanical properties of die-cast copper alloys is crucial for rational material selection, process optimization, and product quality assurance.
The physical properties of die-cast copper alloys are closely related to their chemical composition and crystal structure. Density is one of the fundamental physical parameters of copper alloys, and it varies among different types of copper alloys. For example, the density of brass generally ranges from 8.4 to 8.8 g/cm³ , while that of bronze varies depending on the alloying elements. Regarding the melting point, pure copper has a melting point of 1083 °C. The addition of alloying elements lowers the melting point of copper alloys, significantly impacting temperature control during the die-casting process. Thermal conductivity and electrical conductivity are the most prominent advantages of copper alloys. Pure copper has a thermal conductivity of approximately 398 W/(m · K) and an electrical conductivity of 100% IACS . While alloying reduces its thermal and electrical conductivity, it still outperforms many other metals. The coefficient of thermal expansion (CTE) determines the dimensional stability of copper alloys during temperature fluctuations. This is particularly important for components in precision instruments and equipment. For example, components operating in high-temperature environments require copper alloys with a low CTE to minimize the effects of dimensional changes.
In terms of mechanical properties, die-cast copper alloys exhibit a wide range of characteristics, capable of meeting the needs of diverse applications. Tensile strength refers to the maximum stress a copper alloy can withstand during a tensile test. It reflects the material’s ability to resist fracture. The tensile strength of different grades of die-cast copper alloys varies significantly, ranging from hundreds of megapascals to thousands of megapascals. Yield strength is the stress at which a material begins to undergo plastic deformation. Yield strength is an important reference for components that require minimal deformation during use. Elongation reflects the material’s plasticity. Copper alloys with higher elongation exhibit better formability and impact resistance, making them less susceptible to fracture when subjected to sudden loads. Hardness measures a material’s ability to resist localized deformation. Higher hardness improves the wear resistance of copper alloys, making them suitable for manufacturing easily worn components such as bearings and gears. Impact toughness reflects a material’s ability to resist damage under impact loads. For components operating under dynamic loads, such as automotive drive shafts, impact toughness is a key performance indicator.
Die-casting process parameters have a significant impact on the physical and mechanical properties of copper alloys. Parameters such as the injection pressure, injection speed, pouring temperature, and mold temperature during the die-casting process will affect the microstructure density and grain size of the copper alloy, thereby changing its properties. For example, a higher injection pressure can enable the molten copper alloy to better fill the mold cavity, reduce defects such as pores and shrinkage, and increase the density of the material, thereby improving its mechanical properties. Appropriate pouring temperature and mold temperature can ensure that the copper alloy forms uniform and fine grains during the solidification process, which is beneficial to improving the strength and toughness of the material. Conversely, improper control of process parameters can lead to problems such as loose microstructure and coarse grains in the copper alloy, resulting in a decrease in its physical and mechanical properties. Therefore, during the production process, it is necessary to optimize the die-casting process parameters to obtain copper alloy die-castings that meet the performance requirements.
Different types of die-cast copper alloys have diverse applications due to their composition and properties. For example, brass, with its excellent mechanical and processing properties and relatively low price, is widely used in automotive parts, plumbing equipment, and electrical switches. Tin bronze, with its high strength, hardness, and wear resistance, is suitable for manufacturing wear-resistant components such as bearings, bushings, and gears. Aluminum bronze, with its excellent corrosion resistance and high-temperature strength, plays an important role in shipbuilding, chemical equipment, and other fields. With the continuous advancement of industrial technology, the performance requirements for die-cast copper alloys are becoming increasingly stringent. By adjusting chemical composition and optimizing processes, new die-cast copper alloys with higher performance are being developed, such as high-strength, high-conductivity, and high-corrosion-resistant copper alloys, to meet the needs of high-end industries such as aerospace and new energy. In-depth research on the physical and mechanical properties of die-cast copper alloys will provide strong technical support for their application in a wider range of fields.
