Aluminium Solder Alloy Free from Si Primary Particles and Method for Producing It

An aluminium alloy product, at least partly consisting of an aluminium solder alloy having the following proportions as alloying constituents in percentage by weight:

• 4.5%≦Si≦12%
• and optionally one or more of the following proportions as alloying constituents in percentage by weight:
• Ti≦0.2%,
• Fe≦0.8%,
• Cu≦0.3%,
• Mn≦0.10%,
• Mg≦2.0%,
• Zn≦0.20%,
• Cr≦0.05%,
• with the remainder aluminium and unavoidable impurities, individually at most 0.05 wt %, in total at most 0.15 wt %, wherein boron is additionally provided as an alloying constituent, wherein boron is added to the alloy such that the boron content is at least 100 ppm and the aluminium alloy is free from primary Si particles having a size of more than 20 μm, in particular 10 μm, and the aluminium alloy product is a strip and has at least one further layer consisting of aluminium or of another aluminium alloy.

A method for producing an ingot consisting of an aluminium solder alloy, wherein the ingot is utilizable for producing an aluminium alloy product by rolling, the method comprising the steps of:

• melting pure aluminium with unavoidable impurities, individually at most 0.05 wt %, in total at most 0.15 wt %, in a melting furnace, optionally adding one or more of the following proportions
• Ti≦0.2%,
• Fe≦0.8%,
• Cu≦0.3%,
• Mn≦0.10%,
• Mg≦2.0%,
• Zn≦0.20%,
• Cr≦0.05%,
• to the alloy as further alloying constituents in percentage by weight in the melting furnace or are already at least partially contained in the pure aluminium,
• adding silicon to the alloy in the melting furnace until an Si content of 4.5 wt % to 12 wt % of the aluminium alloy has been reached,
• adding boron to the alloy such that the boron content is at least 100 ppm and the solidified aluminium alloy is free from primary Si particles having a size of more than 20 μm, in particular 10 μm, and
• casting an ingot.