Surface cracking and melting behavior of tungsten-vanadium alloys under thermal shock

Surface cracking and melting behavior of tungsten-vanadium (W-V) alloys prepared by mechanical alloying + hot pressing (HP) sintering under thermal shock has been investigated in this paper. Mass fraction of V in the alloy is taken as a variable to explore the effect of mass fraction of V (1%-10%) on thermal shock resistance of W-V alloys. A variety of test methods such as optical microscope, scanning electron microscope, energy disperse spectrometer, and nano indentation are used to analyze the structure characteristics of W-V alloys produced by HP sintering, and the characteristics of surface cracking and melting behavior of W-V alloys under thermal shock. Results show that under the conditions of 1800℃ and 20 MPa, and with heat preservation for 2 h, W-V alloys with high density and high alloying degree can be produced. Moreover, with the increase of vanadium content, the density of W-V alloys increases. In the alloys, the hardness of tungsten matrix is bigger than vanadium rich phase, and therefore, tungsten matrix's ability of preventing the crack growth is obviously greater than vanadium rich phase, when exposed to thermal shock in international thermonuclear experimental reactor (ITER) edge localized modes (ELMs) which are simulated by high energy electron beam; with the increase of vanadium content, the cracking threshold and melting threshold both decrease. The underlying mechanism is discussed detailed in this paper.