An investigation on the compressive strength enhancing mechanism of directionally solidified Ti-47Al-2Nb-2Cr-0.2Er alloy in case of cyclic loading

In the present study the microstructure evolutions and compressive strengths of the directionally solidified Ti-47Al-2Nb-2Cr-0.2Er alloy undergoing single and cyclic loadings are studied. It is found that bending in lamellar structure can be caused by compression and the extent of this bend exacerbates with the increase of compression strain. For the sample under cyclic-loading, the density of dislocation is improved, resulting in a higher compressive strength in comparison with the sample subjected to single loading with the same strain. Enhancements of Peierls stress, long-range elastic interactions between dislocations, and jog quantity all contribute to the higher strength of the cyclic-loading sample. Dislocation loops releasing from the semi-coherent interfaces under the applied stress are the main dislocation multiplication mechanism during the room temperature compression.