A new type of niobium tungsten alloy element control

To prepare a new niobium tungsten alloy, alloying elements must be selected and controlled first. W, Mo, Zr, Ti and a small amount of rare earth oxides must be added to Nb matrix. These elements will form a variety of solid solution and precipitation strengthening phases with Niobium, which can significantly improve the mechanical properties of the alloy at room temperature and high temperature. Added in the alloy W, Mo, due to the high melting point, these two elements atomic radius and niobium element close, easy to form the substitutional solid solution, can improve the high temperature strength and creep properties of niobium matrix and alloy after adding Zr element, will precipitation strengthening phase at certain temperatures, precipitation strengthening effect, can improve the strength of the alloy matrix. Ti has a great affinity with oxygen. In the air or oxygen-containing medium, a dense, strong adhesion and inert oxide film is formed on the surface of titanium to protect the matrix from corrosion. The addition of rare earth elements can enhance the bonding force between the oxide film and the matrix, thus significantly improving its antioxidant capacity.

C is easy to form strengthening phase with Zr and Ti. By adjusting the content of C and increasing the strengthening phase, the high-temperature strength of the alloy can be further improved.

There are two levels of carbon content in general alloys, namely 500~ 650MgL-1 and 850~ 1000MGL-1. The corresponding relationship between different C content and high-temperature strength of alloys has been obtained through many tests.

From this, the carbon content of the alloy composition can be analyzed

It is obvious that the mechanical properties of the alloy are greatly improved when the carbon content is 850~1000 MgL-1.Therefore, during the preparation of the alloy, the composition of carbon content in the alloy ingots is required to be controlled between 850 and 1000 MgL-1.

Based on the above analysis, a new Nb-W-Mo-Zr series niobium alloy Nb521-1 with constant high and low temperature mechanical properties and thermal strength was prepared by sintering by controlling the ratio of Nb, W and Mo elements, adding Zr, Ti and a small amount of rare earth elements and adjusting the content of C. Its main components are 5%W, 2%Mo, 1%Zr, and the margin is Nb.

Electron beam melting furnace can reduce the content of interstitial impurity elements in alloy, improve the high temperature performance of alloy Nb521-1 through the control of N content in raw materials, improve the sintering process parameters, to extend the time of heat insulation, electron beam melting speed control, makes part of interstitial impurity (N, H, etc.) to volatilize, guarantees the Nb521-1 alloy inherent high temperature and high strength and good plastic quantitative analysis by Nb521-1 alloy compared with C103 alloy element content of impurities, thus it can be seen that interstitial impurity elements in the alloy Nb521-1 had a good control.