A method of determining the proportions of different powders in a powder comprises obtaining a sample of a powder, adding and mixing the sample into a molten material and freezing the mixture of powder and molten material to form a block. Computed tomography is performed on the block to produce a three-dimensional image of the block, the three-dimensional image of the block comprises a first shade, a second and a third shade corresponding to the material, a first powder particle and a sec and powder particle. The three-dimensional image of the block is analyzed to count the number of regions exhibiting the second shade and the third shade corresponding to the number of first powder particles and second powder particles respectively. The fraction of second particles in the powder is determined by dividing the number of second powder particles by the sum of the number of first powder particles and the number of second powder particles.