In this study, a new physically-based finite element approach is proposed to model and predict the superficial oxide layer removal and the occurrence of localized metallic bonding during particle impacts. The process physics, based on explosive welding theory and experiments, and method implementation is presented. Prediction of critical velocity of copper is obtained and compared to experimental data to validate the model. Moreover, the model is also able to show the bonding locations at the interface between particles and substrate. The predicted bonding locations are consistent with experimental data from literature for several metals.

This study is part of an ongoing effort to develop high performance CoNiCrAlY bond coats by means of cold gas dynamic spraying in order to have complete control of bond coat microstructure. As such, the objective of the work presented in this paper is to perform a detailed analysis of cold sprayed CoNiCrAlY layers to assess any changes in microstructure, relative to the original feedstock powder, that may have occurred during layer build-up and compaction. Based on SEM, TEM, and XRD examination results, it is shown that, contrary to the generally accepted theory, important microstructural changes occur during the cold spray deposition process. In the coating samples examined, investigators observed evidence of grain refinement in the CoNiCr γ-phase matrix and partial dissolution of NiAl β-phase precipitates. These changes are a result of severe plastic deformation due to the high-velocity impact of sprayed particles.

This work describes recent progress in Cold Spray of 2618 (Al-Cu-Mg-Fe-Ni) aluminum alloy with Sc addition. Atomized 2618+Sc aluminum powder was sprayed onto aluminum substrates. 2618Al alloy is used for intermediate to high temperature applications in aerospace and automotive industry. The addition of Sc provides higher thermal stability to this alloy by the formation of fine Al 3 Sc particles. The Cold Spray process allows the fabrication of refined microstructure when compared to conventional manufacturing techniques such as casting. The microstructure of the powder and the resulting coating was analyzed using scanning electron microscopy. The mechanical behavior of the powder and the coating was studied using micro indentation measurements. The influence of different heat treatment conditions on the coating was also analyzed. This work shows that Al-Cu alloys with a refined grain structure microstructure can be successfully produced by the Cold Spray process.