Rudimentary investigation of the HIP process for tungsten target

Zr alloy and 316-Ti stainless steel (S.S.) were selected as cladding materials for a W target. The HIP processes were performed at 1200, 1300 and 1400 °C and 180 MPa. The observation and determination for micro-morphology of the interface, diffusion depth and composition as well as their micro-hardness were conducted. The results indicated that the bonding of W–Zr and W–S.S. was good under the testing conditions. No pores or micro-cracks in the interface were observed. Grain growth of W was not observed at 1200 and 1300 °C, but it was observed at 1400 °C. The diffusion of Zr–W on the interface of W–Zr was preferred during the HIP process. The diffusion layer was 6–13 μm in thickness for W–Zr, and 13 μm for W–S.S. A peak of the hardness was observed at the interface of W–Zr or W–S.S. A part of the stainless steel cladding melted after HIP using an oxygen absorber (Zr) at 1300 °C and 180 MPa. The conditions of 1200 °C and 180 MPa without using an oxygen absorber Zr are suitable for W–S.S. bonding, while 1300 or 1400 °C and 180 MPa are better for W–Zr bonding.