Copper and Copper Alloys

Overview

This subsection covers PM materials made from copper, brasses, nickel-silver, and bronze for structural applications, excluding bearings. These materials are manufactured from prealloyed powders, except for pure copper and bronze, which are typically made from admixed elemental copper and tin powders.

Material Characteristics

• PM Copper: Exhibits typical copper color and is valued for its excellent thermal and electrical conductivity. Conductivity varies depending on density, with higher densities resulting in higher conductivity.
• PM Brass: Available in various compositions with zinc content ranging from 10 to 30 wt.%, balanced with copper. Machinability is improved with the addition of 1 to 2 wt.% lead.
• PM Bronze: Contains 10 wt.% tin, balanced with copper. Used in structural applications where strength, corrosion resistance, and appearance are essential.
• Nickel-Silver: Copper alloy with 18 wt.% zinc and 18 wt.% nickel, offering improved corrosion resistance compared to brass.

Applications

• Pure Copper: Utilized in applications requiring excellent thermal or electrical conductivity.
• Brass, Nickel-Silver, and Bronze: Widely used in structural parts requiring good corrosion resistance, machinability, attractive appearance, and ductility.

Microstructure

• After sintering, copper, brass, bronze, and nickel-silver alloys exhibit minimal original particle boundaries. In well-sintered bronze, alpha bronze grains have grown from their original clusters, and no evidence of Cu-Sn intermetallic compounds is present.

Chemical Composition Requirements

The chemical composition for various copper and copper alloy materials is detailed below:

Other Elements: For C-0000 materials, 0.2 wt.% max; for all other copper-based alloys, 2.0 wt.% max.

Selection and Agreement

Optimal material selection requires discussion with the PM parts manufacturer to ensure properties and cost-effectiveness align with the application requirements. Agreement between purchaser and manufacturer on various aspects like strength value, grade selection, chemical composition, and alloying method is crucial to avoid misunderstandings.