Casting material made of a copper-zinc alloy, method for producing a cast product and cast part

A casting material composed of a copper-zinc alloy having the following composition in % by weight:

• Cu:
• 58.0% to 66.0%,
• Si:
• 0.15% to 1.2%,
• P:
• 0.20% to 0.38%,
• Sn:
• optionally up to 0.5%,
• Al:
• optionally up to 0.05%,
• Fe:
• optionally up to 0.3%,
• Ni:
• optionally up to 0.3%,
• Pb:
• optionally up to 0.25%,
• Bi:
• optionally up to 0.1%,
• Te, Se, In each optionally up to 0.1%,
• B:
• optionally up to 0.01%,
• balance:
• Zn and unavoidable impurities,
• where the proportion of unavoidable impurities is less than 0.2% by weight,
• where the alloy has a microstructure composed of α phase, β phase and phosphide particles, and the proportion of the β phase in the sum total of α phase and β phase is at least 20% by volume and at most 70% by volume, where silicon is present both in the α phase and in the β phase, where, in an area of 21 000 μm2, there are 20 to 300 phosphide particles having an equivalent diameter of 0.5 to 1 μm, 30 to 120 phosphide particles having an equivalent diameter of 1 to 2 μm, and 20 to 100 phosphide particles having an equivalent diameter of 2 to 5 μm, and where the proportion of the β phase and the Preliminary Amendment-Page 3 proportions of Si and P are chosen so as to satisfy the condition
• 92.724
• 9
• -
• 0.473254
• ·
• [
• beta
• ]
• -
• 80.6378
• ·
• [
• Si
• ]
• -
• 1
• ⁢
• 4
• ⁢
• 2
• ⁢
• .65
• ·
• [
• P
• ]
• +
• 2
• ⁢
• 7
• ⁢
• 9.309
• ·
• [
• Si
• ]
• ·
• [
• P
• ]
• <
• 40
• where [beta] denotes the proportion of the β phase in % by volume, [Si] the proportion of silicon in % by weight, and [P] the proportion of phosphorus in % by weight.