| Abstract Scope |
There are a variety of materials manufacturing technologies that rely on kinetic impacts to achieve additive material build-up, including, notably, cold spray and laser-induced forward transfer. The unit processes of these manufacturing paradigms involve small quantities of material (micrometer scale particles) and extremely high velocities (~ km/s), so the impact events involve a number of fundamental physical mysteries at the extremes of materials mechanics. This talk will overview our efforts at developing quantitative in-situ methods to study such impacts, involving strain rates up to about 108 s-1. Using an all-optical test platform to launch and observe the impacts, we are able to provide insight on the mechanics of shock and spall, bond formation, and erosive wear. By systematically exploring a range of materials with different properties, we develop a picture of the controlling physics of bonding, which includes mechanical properties (elastic and plastic), thermal properties (related to adiabatic heat), and surface films. The talk will review our work on a variety of pure metals and engineering alloys and will also provide a view on new issues that arise in advanced materials like metallic glasses. |