Based on differences in chemical composition and structural components, common hard alloys can be categorized into steel-bonded hard alloys, tungsten-cobalt alloys, tungsten-titanium-tantalum-cobalt alloys, and Tungsten-Titanium-cobalt alloys, with their physicochemical properties and applications being largely similar.

Phosphorus element, as a typical harmful impurity in tungsten-nickel-iron alloy, is typically controlled to below 0.01%. Even in trace amounts, it influences the alloy’s mechanical properties, corrosion resistance, and processing stability through grain boundary segregation and compound precipitation.

Composite tungsten electrode materials can be categorized into thorium-tungsten electrodes, cerium-tungsten electrodes, yttrium-tungsten electrodes, zirconium-tungsten electrodes, and lanthanum-tungsten electrodes, depending on the additives used. Although all these tungsten electrodes are primarily made from the refractory metal tungsten, their physical and chemical properties and applications vary slightly due to differences in modifiers.

Sulfur element predominantly exerts harmful effects on tungsten-nickel-iron alloy performance: its impact is minimal at low levels, but excessive sulfur content leads to the formation of low-melting-point sulfides and grain boundary weakening, resulting in a sharp decline in impact toughness, deterioration of strength and plasticity, reduced corrosion resistance, and hindered processability.