Investigation On The Effect Of Mechanical Vibration On Dynamic Mechanical Properties Of Typical Molybdenum Alloy

Molybdenum alloy components serving in mechanical vibration environment for a long time are prone to create vibration cracks,thus changing their dynamic mechanical properties during service.there are few studies on the dynamic mechanical stability,vibration energy consumption mechanism and vibration fracture failure mechanism of molybdenum alloy structural parts under mechanical vibration environment,which brings limitations to the development and application of molybdenum alloy components serving under mechanical vibration load conditions.Therefore,it is crucial to simulate the real vibration service environment of typical molybdenum alloys and study the influence of mechanical vibration on the dynamic mechanical behavior of typical molybdenum alloys.In this paper,the effect of mechanical vibration frequency on the dynamic mechanical properties of typical molybdenum alloys was analyzed by conducting mechanical vibration experiments at frequencies of 100 Hz,150 Hz and 200 Hz for Mo,Mo-Re and ODS-Mo alloys,respectively.Subsequently,the effect of temperature on the dynamic mechanical properties of typical molybdenum alloys was investigated by subjecting them to variable temperature mechanical vibration at 0℃ ～-110℃ and 25℃ ～ 350℃,respectively.The vibration fracture failure behavior of typical molybdenum alloys after mechanical vibration is discussed,and the energy consumption mechanism and vibration failure mechanism of typical molybdenum alloys during mechanical vibration are revealed.The results show that alloying can change the grain size and shape of molybdenum alloy.The addition of Re element significantly reduces the grain size of Mo-Re alloy.The second phase particles in ODS-Mo alloy can become nucleation particles in powder sintering,hinder the migration of grain boundaries and transform the grain shape into equiaxed grains.The dynamic mechanical properties of typical molybdenum alloys at different mechanical vibration frequencies are essentially the difference between intergranular friction terms.The energy storage efficiency of Mo-Re alloy is much higher than that of the other two molybdenum alloys at the initial stage of mechanical vibration.The existence of the second phase particles also makes the storage modulus of ODS-Mo alloy at a higher value at different mechanical vibration frequencies.When the mechanical vibration frequency is 150 Hz,Mo alloy exhibits transgranular cleavage fracture,Mo-Re alloy exhibits brittle intergranular fracture,and ODSMo alloy exhibits transgranular-intergranular mixed fracture.The dynamic mechanical properties of Mo-alloy and ODS-Mo alloy under lowtemperature mechanical vibration are greatly affected by temperature.The low-temperature rhenium effect in Mo-Re alloy makes its mechanical properties more stable under lowtemperature mechanical vibration.The vibration reduction and resilience performance of typical molybdenum alloy under high-temperature mechanical vibration is mainly determined by its intergranular and intragranular friction terms.The compressive stress of the crystal plane of typical molybdenum alloy increases significantly with the increase in temperature,which reflects the increased intergranular friction term.At the same time,the intensification of atomic diffusion behavior positively affects the high-temperature vibration reduction resilience of typical molybdenum alloys.High-temperature mechanical vibration cracks all initiate at the prefabricated V-shaped notch.The high-temperature mechanical vibration fracture failure behavior of Mo-alloy and Mo-Re alloy shows typical vibration fatigue fracture morphology,and the high-temperature mechanical vibration fracture failure behavior of ODS-Mo alloy shows typical intergranular fracture morphology.The cross-slip of screw dislocation and the coordinated micro-rotation of multiple grains determines the mechanical vibration failure mechanism of Mo-alloy and Mo-Re alloy.The pinning dislocation of the second phase particles and the decrease of grain boundary strength determines the mechanical vibration failure mechanism of ODS-Mo alloy.