The parameters you mentioned for aluminum alloy welding powder, such as "high purity," "fine," and "7075," describe the material's surface quality and chemical composition. High-purity refers to the high degree of purity in the powder, which can make it ideal for use in high-strength applications that require good surface coverage. Fine refers to the small size and roughness of the powder, making it suitable for use in applications with precise control over the quality of the material's finish. 7075 refers to the fine powder type of aluminum alloy, which is commonly used in aerospace and automotive industries due to its high strength-to-weight ratio and lightweight weight.