Study On Preparation And Toughening Mechanisms Of Multiple Doping Strengthened Molybdenum Alloys

Molybdenum was discovered in1778by,C.W.S cheele, It is a structural material,which has a high melting point, high strength, high hardness. Molybdenum is the raremetal with strategic significance, it is an important foundation for the development ofhigh technology, modernization of the country, building a modern national defensematerials and widely used in iron and steel industry, electronic industry, aviation andnuclear technology, metal pressure processing, chemical industry coating, pigment andcatalyst etc. But when the temperature is at or above the recrystallization temperature,molybdenum material will be obviously brittleness, high temperature strength isdecreased significantly, therefore, its application is greatly restricted. The strength andtoughness of molybdenum can be improved by adding trace elements Ti, Zr in it. Sohigh temperature molybdenum alloy has a wider range of applications in hightemperature areas, because of its high recrystallization temperature, good strength athigh temperature and low temperature toughness. But the studies on the impact ofadding elements on properties of high temperature molybdenum alloy is very rarely athome and abroad, do not form a complete theoretical system. So the research aboutjoin form and adding amount is very meaningful.In this paper, preparation of different join form and the amount of TZM alloy bythe method of powder metallurgy sintered, Finally sintered with four different Ti, Zrjoined form were obtained. the density and hardness of sintered were tested, stressstrain curve and high temperature deformation behavior of TZM alloy billets wereinvestigated by thermal Simulator at1300°C and1400°C, to determine the best joinedform. The Microstructure of the TZM alloy, high temperature rolling of the plate wasanalyzed by using detection methods, including XRD, SEM, EDS, TEM and so on.Finally main conclusions are as follows:The properties of molybdenum alloy added with Ti, Zr and other elements havebeen greatly improved, There are a large number of Ti and Zr oxides, elemental and carbide particles, their presence can hinder dislocation movement, resulting in thestrengthening effect in the organization of the TZM alloy.Ti, Zr elements can improve the property of matrix by solid volume, second phasein alloy. Comparative analysis found that micro-hardness of four different joined formswas higher than pure molybdenum at high temperatures. Micro-hardness of the samplewith the Ti content about0.6%was maximum; micro-hardness of the sample with theZr content about0.07%was maximum at room temperature.The experiment found that deformation resistance was decreased along with theincrease of the temperature, high temperature deformation resistance of four joinedforms was higher than that of pure molybdenum, deformation resistance of specimenwith TiH₂-Zr joined form was larger under the high temperature. At1300°C and1400°C, deformation resistance of sample with Ti element addition amount of0.8%was maximum, due to the large presence of oxides. deformation resistance wasmaximum when Zr content in0.07%.