Investigation of solution acidity influence on the morphological structure and physical and mechanical properties of particle-reinforced tungsten alloys

摘要

Yttria-stabilized zirconia particle-reinforced tungsten alloys were fabricated by using azeotropic distillation process coupled with powder metallurgy techniques. The influence of pH value of the original solution on the precursor powders' morphology and wear and mechanical properties of alloys was deeply studied. It showed that the precursor powder synthesized under solution with pH of 2 possesses finer particle size. The grain sizes of tungsten reinforced alloys obtained with different pH values vary from 2 to 6 mu m, extremely smaller than that of pure tungsten. When pH value increases from 2 to 8, more and more bonding zirconia particles are obtained. The reinforced tungsten alloy prepared based on the solution of pH equal to 2 has better morphological and mechanical properties than the other two alloys prepared based on the solution of pH values of 5 and 8, respectively. The wear resistance of the reinforced tungsten alloy increases firstly and then decreases with the doping amount of zirconia particles. It is confirmed that the pH 2 value and chemical composition of the tungsten alloy with 3.0 wt. Zr(Y)O-2 exhibit the best wear resistance. The mechanical properties of the particle-reinforced tungsten alloy are improved with the decrease of pH value. The ultimate compressive strength and ultimate strain values of pH 2 reach to 1009 MPa and 0.23, respectively. The evolution of the relative density and associated porosity increases with the pH value. The abrasion mechanism was analyzed in detail.