Room temperature deformation of single crystals of Ti(5)Si(3) with the hexagonal D8(8) structure investigated by micropillar compression tests

Micropillar compression tests of Ti(5)Si(3) single crystals were conducted at room temperature as a function of loading axis orientation and specimen size in order to investigate their room temperature plastic deformation behavior. Plastic flow by the operation of three deformation modes, {1[Formula: see text] 00}[0001], {2[Formula: see text] [Formula: see text] 2} < 2[Formula: see text] [Formula: see text] [Formula: see text] > and {1[Formula: see text] 01} < 2[Formula: see text] [Formula: see text] [Formula: see text] > slip were observed in [2[Formula: see text] 05]-, [0001]- and [4[Formula: see text] [Formula: see text] 0]-oriented micropillar specimens deformed at room temperature, respectively. The CRSS values were evaluated to be very high above 2.7 GPa and were confirmed to increase up to about 6 GPa with the decrease in the specimen size. The fracture toughness values are evaluated to be 0.45 MPa m(1/2) (notch plane // (0001)) and 0.73 MPa m(1/2) (notch plane //(1[Formula: see text] 00)) based on the results of micro-cantilever bend tests of chevron-notched specimens. The fracture toughness values are considerably lower than those for D8(l)-Mo(5)SiB(2) and D8(l)-Nb(5)Si(3) evaluated by the same method, indicating the inherent brittleness of binary Ti(5)Si(3) compared to the other transition-metal silicides of the TM(5)Si(3) type (TM: transition-metal).