Macro And Micro Mechanical Properties Analysis Of Tungsten Alloy And Its Dynamic Experiment Studies

The Tungsten Alloy is a two-phase material made of W-particle and matrix. W-particle is a highly strength phase, and Bcc W-particle distributes uniformly in the soft Fcc matrix. Under the external applied load, W-particle exhibits extremely high strength, and under the high stress of 2000MPa, its fracture will be a cleavage, also a brittle failure. Ni-Fe, the main component of matrix, has a low melting point. So, it can change into liquid when sintered, thus it can bond the W-particle. This paper is mainly concerned with the following studies:The volumn fraction, configuration and micro distribution of the W particles are the important factors to the tungsten alloy properties. The micro-hardness and micro-elastic-modulus of matrix in tungsten alloy were respectively measured. Using the finite element method with load-displacement relationships obtained from nano-indentation experiments, the parameters of the macro-yield strength and hardening modulus of matrix in the tungsten ally were given. Using the inverse method the micro elastic-plastic properties of the matrix in tungsten alloy were obtained, i.e. through three-dimensional finite element computations with load-displacement relationships obtained from nano indentation experiments, the parameters of the micro-yield strength and micro-hardening modulus of matrix in the tungsten alloy were given. In order to verify the validity of this method the macro experiments were performed and the results of the experiments illustrated that it was valid to determine the micro properties by using the inverse method. Therefore the elastic-plastic properties of the matrix in tungsten alloy were obtained. From the results of the nano indention test the macro material characteristics are the average statistic value of the micro properties. The number of the data points is finite not to express this average affect till the data points are enough and the macro and micro results will be consistent. It provided the basis for studying the relationships of macro-mechanical behaves with micro- structures of tungsten alloy.The tension experimental data of tungsten alloy were processed by back-propagation (BP) Neural Network method, including the influences of the W content and deformation magnitude on the tensile strength. Thus two relation curves were drawn, which illustrated the relation between deformation magnitude and material tensile strength whenW contentswere changed, and the relation betweenW contents and material tensile strength in the case of different deformation magnitude. It is shown that BP Neural Network may be used to predict the trend of tensile strength of WHA with the changes of shapes and volume fractions of w-phase. Also, the dynamic compression and tension properties of the tungsten alloy were tested by the splited Hopkinson pressure bar and the pneumatic tension bar. Bodner-Partom model and the Zerilli—Armstrongmodel were used to simulated the tension and compression test and it was shown that the tension and compression properties of the tungsten alloy is non-symmetric.