Molybdenum tungsten alloy
Molybdenum base alloy containing 25% and 30% tungsten, with good corrosion resistance of molten zinc, can be used to make molten zinc pump and electrolytic zinc electrode and filter molten zinc.
Temperature characteristic
The melting point of Mo-W alloy increases with the increase of tungsten content. When tungsten content increases to 25%, the melting point of molybdenum-tungsten alloy increases about 200℃ compared with that of pure molybdenum. Therefore, the alloy composition can be selected in the range of 2620 ~ 3410℃ according to the operating temperature and the required melting point of the alloy. This advantage is also one of the advantages of Mo-W alloy to be widely used.
The lattice constant
The lattice constants and densities of mo-W alloys increase linearly with the increase of tungsten content. The hardness and strength of molybdenum-tungsten alloy are basically improved with the increase of tungsten content and hardness alloy at the highest room temperature hardness value between 90% ~ 100% tungsten content, its Vickers hardness value is as high as 3530 ~ 3860MPa, more than one times higher than pure molybdenum. The highest high temperature hardness of the alloy is between 70% ~ 85% tungsten content. When the tungsten content increases from O to 40%, the tensile strength of machined mow alloy increases from 617MPa to 900MPa at room temperature.
Preparation Methods The billet of molybdenum and tungsten alloy can be produced by powder metallurgy, vacuum arc melting and vacuum electron bombardment melting. Powder metallurgy is the most widely used method, because the process is simple and can obtain alloy billets with fine grains, which is beneficial to plastic processing. Powder metallurgy process is: molybdenum powder and tungsten powder according to the proportion of mechanical mixing; Through mechanical press or isostatic press pressed into raw; Then the alloy billet is sintered in a high temperature sintering furnace through hydrogen. The sintering temperature increases with the increase of tungsten content and ranges from 2150 ℃ to 2300℃. Finally, the sintered billet is rolled or forged into material.
