Erosion Mechanisms of Metals.

The objective of this program is to identify the material properties which control erosion, as well as the material removal process. Based on previous experimental work, an erosion model has been hypothesized and is based on the target stress-strain response beneath the impacting particle. At low particle energies only elastic strain is generated and no damage to the target occurs. At higher energies, the peak stresses increase, leading to brittle fracture or plastic deformation accompanied by adiabatic heating. If adiabatic heating occurs, three possibilities arise. One is a temperature increase with no loss of material, and the second is that ductile fracture may occur due to inadequate ductility at whatever temperature is reached. The third is that localized regions attain the melting point prior to ductile fracture. A complete relationship exists between strain rate, adiabatic heating, and erosion rate. Erosion rate experiments using various particle sizes and velocities and target materials were performed in order to study this relationship. Target materials of 1095 steel, 2024 aluminum and pure molybdenum, copper, and gold were used as well as three Fe-Cr binary alloys.