Bimetallia

Bimetallia is a term used in metallurgical discourse to describe materials that integrate two metallic components within a single system. It is not a single defined material but a broad concept that covers both homogeneous alloys containing two elements in specific proportions and layered or bonded configurations in which two distinct metals are joined to form a composite.

Two main structural forms are described. In homogeneous bimetallia, the two metals form a single phase, such as a solid solution or an intermetallic compound with fixed stoichiometry, resulting in a uniform composition throughout. In layered or bonded bimetallia, two metals are present as separate layers or regions that are joined by diffusion, welding, or mechanical bonding, producing a composite whose properties reflect both metals and the interface.

Properties depend on the constituent metals and the method of combination. These materials can offer a balance of strength, hardness, wear and corrosion resistance, or distinct electrical and thermal conductivities not present in either metal alone. Ductility and toughness may vary, particularly in intermetallic systems or certain clad configurations.

Manufacturing approaches include melting and alloying, powder metallurgy, diffusion bonding, and clad techniques such as roll bonding or explosive bonding to create layered plates or sheets. Post-processing may include heat treatment and surface finishing to optimize interface strength and performance.

Common applications range from mechanical components like bearings and gears to corrosion-resistant surfaces and electrical contacts. Classic examples include bimetallic strips used in thermostats and clad plates where a base metal such as steel is bonded to a more resistant layer such as nickel or aluminum. The term remains somewhat heterogeneous in usage, reflecting a spectrum of two-metal systems.