A universal shear-lag model for accurate assessment of whisker load-transfer strengthening in metal matrix composites

Abstract

Accurate assessment of the strengthening contribution of whiskers is crucial for the design, development, and application of high-performance whisker reinforced metal matrix composites (WRMMCs). The present work presents a novel universal shear-lag model to accurately calculate the load-transfer strengthening of whiskers in all WRMMCs regardless of matrix and reinforcement. This model considers the tensile strength of whiskers and the stress transfer from the matrix to the whisker ends. The present model provides a facile way to allow consideration of the influence of whisker orientation and aspect ratio distributions on whisker load-transfer strengthening by introducing probability density functions. Their distribution characteristics have a significant effect on the predicted results, which cannot be simply replaced by their average values. The present model was verified by the reported experimental results and comparison with other models, and it shows better agreement. Moreover, titanium matrix composite reinforced with misaligned TiB whiskers was prepared by vacuum arc remelting and hot-forging. TiB whisker aspect ratio and orientation distributions were quantified by image statistics and pole figure analysis. The anisotropy of yield strength was evaluated under monotonic tensile loading in various directions of the composite. Different shear-lag models were applied to evaluate the load-transfer strengthening of TiB whiskers at different angles relative to the tensile loading direction. The present model gave a more accurate prediction of the anisotropy of yield strength than other shear-lag models.