Mechanical properties and microstructure of 91W-Ni-Fe-Co alloys at room temperature and low temperature
91W-5.5Ni-3.3Fe-0.2Co and 91W-5.5Ni-2.5Fe-1Co alloys were prepared by powder metallurgy method.The microstructure evolution and mechanical behavior at room and low temperatures of the alloy were studied using methods such as hardness testing,tensile testing,scanning electron microscopy(SEM)and energy dispersion spectroscopy(EDS).The results show that at room temperature,the mechanical properties of the alloy with 1％Co mass fraction are better,the tensile strength and elongation are 1 400 MPa and 11.7％,respectively.The tensile fracture behavior is mainly tungsten cleavage fracture and bonding phase tearing.In the microstructure,compared with low Co mass fraction alloy,the grain size of the high Co alloy is finer,the tungsten-tungsten continuity decreases,matrix volume fraction increases,and the solubility of tungsten in the matrix increases.As the temperature decreases,the strength of the two alloys increases and the elongation decreases.At-60℃,the elongation of the high Co alloy is 20％higher than that of the low Co alloy,while the fracture mode of the alloy is still matrix rupture.However,the fracture of low Co alloy is dominated by tungsten cleavage fracture after the temperature is lower than-20℃.The increase of Co mass fraction in a certain range can inhibit the segregation of impurity elements at grain boundaries,increase the degree of plastic deformation of tungsten particles,and improve the low-temperature brittleness.
tungsten heavy alloyscobaltmechanical propertiesfracture modelow temperature brittleness
万方数据
