Aluminum Alloys with a content of 22 wt.-% were spray formed. This alloy features by a low density and is therefore a superior material for leightweight applications. The main problem in spray forming of this type of alloy was the occurance of high porosities. First process optimizations have been performed to decrease porosity under a certain level, so that it can be closed by an extrusion process

In Spray Forming, specific enthalpy is a key parameter in the deposition process as it influences the thermal condition of the impinging droplets as well as that of the deposit surface. An empirical model for the distribution of specific enthalpy in the spray cone was developed as an easy to handle alternative to numerical models with which the descriptive partial differential equations are solved numerically. The model results were compared with the experimental data to validate its applicability.

Porosity in spray-formed materials is an important issue, but the formation of porosity is not completely understood. The paper gives some examples picked from literature, which show some general correlations between process parameters and porosity. To improve the understanding of porosity formation it is necessary to know more about the conditions of the droplets and the deposit at the point of impingement. Determining the impact conditions is a challenge because usually they are not constant with time and some values are difficult to measure. Our experiments show a strong correlation between the deposit surface temperature and the porosity. The average impact angle weighted by the local particle mass flux is also an important parameter.