The fundamental difference between alloys and pure metals lies in their composition and performance characteristics. Pure metals are composed of a single element, such as pure iron or pure copper, whereas alloys are formed by melting two or more metals or non-metallic elements together. This combination not only alters the material's microstructure but also significantly enhances its mechanical properties, corrosion resistance, and other physicochemical characteristics.

       1. Mechanical Properties: Pure metals typically exhibit lower hardness, strength, and toughness. For instance, pure copper has a Vickers hardness of approximately 35 HV, whereas brass with 5% zinc addition can achieve a hardness of up to 150 HV.

       2. Corrosion Resistance: Pure iron is prone to rust in humid environments, but stainless steel, which incorporates 18% chromium, can significantly extend its salt spray corrosion resistance from 72 hours to over 1,000 hours.

       3. Microstructure: During the alloying process, solid solutions or intermetallic compounds may form. For example, silicon in aluminum alloys forms eutectic phases, thereby reducing the material's melting point.

       Alloys are widely used in modern industry, particularly excelling in aerospace, medical implants, and equipment manufacturing under extreme conditions. For instance, magnesium-aluminum alloys are employed in aircraft seat skeletons, reducing weight by 30% while maintaining high strength; titanium alloys, renowned for their excellent biocompatibility and strength, are commonly used in medical implants; and nickel-based alloys retain high strength and stability even in high-temperature environments.

Titanium alloy is a type of alloy known for its lightweight, high strength, and excellent corrosion resistance, but it is relatively expensive and suitable for applications with stringent performance requirements.