Tan Chengwen

Effect of the β Phase on Compressive Mechanical Property of CVD Tungsten

Abstract The high pure W (HPW) was deposited on the surface of purity Cu tubes through WF 6 reduction by H 2 adopting cold-wall atmospheric pressure CVD system. Results show that the compressive strength of the tungsten tube with the mixture phase deposited at 440 °C is much lower than that with only α phase deposited at 540 °C. The existence of β phase has a significant negative influence on the compressive property. After annealing treatment at 400 °C for 1 h, the β phase in the mixture will disappear, and its compressive strength reaches the level of the as-deposited α -W.

Damage Mechanisms for 93W and 97W Tungsten-Based Alloys

Abstract Dynamic compression and in-situ tensile tests were carried out for two kinds of W-Ni-Fe alloys with 93wt% and 97wt% tungsten contents fabricated by P/M technique; their microstructures and damage model were examined and discussed. The damage mechanisms for 93wt% W alloy belongs to ductile separation of W-W interface, and that for 97wt% W alloy belongs to initiation and propagation of microcracks inside tungsten grains. On the base of Ostwald ripening theory for the sintering process, the microstructures of the two kinds of alloys with different tungsten volume fractions under various sintering conditions were predicted, and the results agreed with the tests very well. With the help of Ostwald ripening and micromechanical theory, we set up a relationship for sintering condition, volume fraction of tungsten and mechanical properties to help material design, production and mechanical property prediction.