Preparation of hot-rolled potassium doped tungsten (KW) thick plate and performance of KW-Cu monoblock mock-ups under high heat flux testing

Abstract

A 10-kg thick potassium doped tungsten (KW) plate with 70% deformation was prepared by hot rolling. After annealing (1800 °C, 1 h), the typical dovetail splicing morphology was formed which was related to the clustered potassium bubbles in the matrix. Both the as-received KW and annealed KW had the ductile brittle transition temperature (DBTT) less than 250 °C. Taken from this plate, KW-Cu monoblock mock-ups for divertor were manufactured by hot isostatic pressing (HIP) method. High heat flux (HHF) test (1000 cycles at 15 MW/m2) was carried out on the KW-Cu monoblock mock-up by the electron beam thermal shock equipment. The surface damage and recrystallization behavior of the KW-Cu monoblock mock-up were investigated by metallographic means. After HHF test, no debonding at the KW-Cu interface or penetrating cracks of the KW block was found. The tested KW-Cu monoblock mock-up had similar microstructure to annealed KW. Potassium bubbles promoted the unique recrystallization morphology, which was the key to ensuring good high temperature performance of KW.

Keywords

• KW plate
• Monoblock mock-ups
• Thermal shock
• Recrystallization morphology
• Potassium bubble