Substructure of high temperature compressed titanium alloy IMI 834

The substructure of IMI 834 was studied by transmission electron microscopy (TEM). The samples were compressed at 1050 degrees C at two different strain rates, 0.01 and 0.1 s(-1) to a total strain of 0.2. Compared to the as-received microstructure, coarsening of alpha platelets was found after the compression at both strain rates. Recovery of the compression microstructure was observed in the high strain rate compression sample. A majority of the dislocations was identified as < a > type, although some < a + c > type dislocations were also found. Retained P phase and silicides show strong resistance to the glide of dislocations. This results in the pileup of dislocations at the vicinity of retained P phase and the formation of low angle subgrain boundaries. Interactions of < a > and < a + c > type dislocations on the pyramidal planes {1 (1) over bar 0 2} were observed to form hexagonal dislocation networks. The observed substructure differences resulting from different strain rates indicate that forging speed will influence microstructure development of the IMI 834 alloy. (c) 2006 Elsevier B.V. All rights reserved.