Introduction

Process for making a joint between dissimilar materials, a tungsten-based element and a copper alloy metal element. In particular, it is a method of joining elements subject to high thermomechanical stresses, such as plasma facing units (PFUs) present inside a fusion machine.

Technical features

The technology uses a copper-chromium-zirconium alloy (CuCrZr), subjected to an appropriate heat treatment, as an intermediate layer (interlayer) for the junction between CuCrZr alloy tube and W tungsten monobloc in order to improve fatigue resistance performance. under neutron irradiation of the component. The welding between W and solubilized CuCrZr takes place by atomic diffusion at high temperature in a high-vacuum furnace. Through the use of a cylindrical stainless steel pin inserted inside the tube during the thermal cycle, it can improves the contact between the surfaces to be welded, obtaining a superior quality joint. The current technology,  taken into consideration by ITER Project but also by the EU-DEMO one,  provides for the presence of an intermediate layer in ductile material (OFE or OFHC copper), this material, exposed to neutron radiation, shows a reduction in both maximum strength and fatigue resistance and a severe embrittlement with possible consequences on the quality and tightness of the joint.
TRL: 4

Possible Applications

• Industrial and laboratory applications;
• Fusion and metallurgical areas.

Advantages

•  Improvement of the performance component exposed to neutron irradiation.