Abstract 

The need for high accelerating gradients for the future Compact Linear Collider (CLIC) imposes considerable constraints on the materials of the accelerating structures that are peculiar to the high electric field regions and to the high magnetic field regions. The tips of the irises, where  electric field is maximum, are prone to break down and field emission resulting in modification of the cavity shape. The cavity surfaces, where magnetic field is maximum, are submitted to cyclic thermal stresses induced by high pulsed RF currents possibly resulting in surface damage by fatigue.  
Pure copper has shown its limitations to cope with those constrains. Structures with regions made of two different materials have been proposed where the tips of the irises will be of pure molybdenum (or an alternative refractory alloy) and the main walls of the cavities will be of CuZr alloy UNS C15000 (or an alternative copper alloy with the best matching of electrical conductivity and fatigue resistance properties). Such structures have to be manufactured from bi-metallic raw materials that are not commercially available. A suitable way of producing Mo-CuZr semi products compatible with the manufacturing and operation of structures has to be developed and assessed. 
In this talk different possibilities of obtaining bi-metallic raw materials for manufacturing of structures will be presented, together with the characterization of prototypes obtained by four different ways. In particular the results of the characterization of the two more promising bimetals obtained to date will be presented: HIP (High Isostatic Pressure) diffusion bonding and explosion bonding techniques will be compared in terms of their limitations and perspectives.