Aluminum Grain Refinement via Titanium-Boron
Titanium-boron is added to the melt to produce a fine casting structure through heterogeneous nucleation. This improves mechanical properties and prevents porosity.
Physico-Chemical Mechanism
Titanium-boron reacts with aluminum in the melt to promote heterogeneous nucleation. These nuclei serve as core points for crystal growth and lead to a finer casting structure.
Metallurgical Relevance & Risks in Welding
A fine casting structure increases the mechanical properties of aluminum, such as strength and toughness. It also prevents porosity and improves corrosion resistance. However, missing or excessive titanium-boron additions can lead to uneven melting behavior and lack of nuclei, resulting in a coarser casting structure and potential cracks in the final product.
Workshop Practice & Instructions
Titanium-boron should typically be added to the melt at a scale of 0.1 to 0.5%. The exact amount depends on the desired casting structure and the specific aluminum alloy. Ensure that the titanium-boron master alloy is well dissolved in the melt to achieve a homogeneous distribution.