Alloying of molybdenum-TZM ALLOY, REE, AND OTHERS METHODS

MIRAMAR, Fla. - April 8, 2022 - PRLog -- The alloying principle of molybdenum is similar to that of tungsten. All the strengthening methods used to improve the heat resistance of tungsten are basically applicable to molybdenum. There are mainly the following types: solid solution strengthening, precipitation strengthening, dispersion strengthening and composite strengthening.
Solution strengthening
Solid solution strengthening includes the addition of trace elements and high content elements.
The trace element solid solution strengthening method mainly refers to adding a trace amount of Ti, Zr, Fe, Mn, La, B and other alloy elements for solid solution strengthening to improve the performance of molybdenum (https://www.edge-techind.com/category/Molybdenum-23-1.html).
High content element solid solution strengthening
The elements that improve the binding force between atoms of the molybdenum alloy and form a continuous solid solution are tungsten, tantalum, and rhenium.
Molybdenum precipitation strengthening

The addition of titanium, zirconium and other active elements in molybdenum and the carbides generated by the reaction of carbon form a supersaturated solid solution during the high-temperature quenching of the alloy. This solid solution precipitates fine and dispersed titanium carbide and zirconium carbide particles during the subsequent annealing. Taking TZM alloy (https://www.edge-techind.com/category/Molybdenum-Alloys-6...) as an example, the alloy contains 0.40%-0.55% of titanium (mass fraction, the same below), zirconium 0.06%-0.12%, carbon 0.01%-0.04%, both titanium and zirconium are dissolved in molybdenum, solid solution strengthening It also reacts with the interstitial element carbon to form a compound titanium zirconium carbide.

Molybdenum compound strengthening

(1) Oxidation strengthening. Al2O3, MgO, ZrO2, etc. are commonly used strengthening molybdenum strengthening agents. In recent years,

Adding molybdenum to molybdenum to form an oxide dispersed phase can achieve the purpose of better strengthening the molybdenum alloy. The rare earth elements (https://www.edgetechree.com/) used are Y,La, Ce, Nd, Sm and Cd, among which Y, Ce and La are the most commonly used, and the number of oxides they form in molybdenum is generally controlled Controlled at about 1% (mass fraction).

(2) Doping strengthening (potassium bubble strengthening).
Molybdenum reinforced compound

The composite strengthening of molybdenum is to apply the above two or more strengthening mechanisms to molybdenum at the same time, so that molybdenum can obtain a better strengthening effect. Common compound reinforcements are

(1) Solid solution strengthening + precipitation strengthening.
(2) Dispersion strengthening + precipitation strengthening
(3) Relay enhancement. For molybdenum alloys, the temperature range of solid solution strengthening is between 1100 and 1300°C, and it will fail at higher temperatures.
The development of composite strengthened alloys to achieve the effect of relay strengthening in different temperature zones is one of the directions for the development of high strength heat resistant molybdenum alloys.