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A physics model was established for describing the particle size distribution of beryllium (Be) powder produced by impact attrition milling. In this model, two factors were considered: the first, the distribution of existing state of particles with different original kinetic energy should obey the Maxwell-Boltzmann statistics after impacted, it was that, being at higher energy level made big particles unstable, which were easy to be fractured into smaller pieces in impact attrition process, this influencing factor described as the negative exponential of particles size; the second, the tendency to remain low surface energy needed particles should keep big volume as much as possible, this effect defined as the cube of particles size. The actual particle size distribution of Be powder was resulted from the competition between these two factors. Calculating result from the model was in good agreement with data from measurement.

For polycrystalline Beryllium (Be) specimens, data of yield strength, ultimate strength, elastic modulus, inelastic secant modulus elongation and grain size were obtained by using of material testing machine and metaloscope. It showed that: elastic modulus, inelastic secant modulus were basically independent with grain size; ultimate strength appeared at the end of tension process; relation between rate of yield strength to ultimate strength and elongation was found to be linear, but this rate had no clear correlation with grain size; relation between strength (yield, ultimate) and grain size was satisfied with Hall-Petch equation. Based on test data and analysis above, a bilinear model was given to simulate stress-strain constitutive behavior; an equation expressing relation between elongation and grain size was also derived.

A numerical analysis was performed to investigate the thermally-induced residual stress caused by the thermal expansion mismatch between Be and BeO. Models were constructed according to the real situation that the BeO particles embedded in grains or distributed at the grain boundaries, where the temperature-dependent materials properties, particle volume fraction and size and interparticle distance were taken into account. In simulation, it supposes particles inside grain no interacting with others, particles along the grain boundary being a period distribution. Be is modeled as elastic and elastic-plastic material with bilinear kinematic hardening model. BeO is modeled as isotropic and linear elastic. All simulations are performed by using ANSYS finite element code. Results show that the size, location and the volume fraction of particles influence on the residual stress (strain) to different extent during cooling process.