Response of the solidification microstructure of a high Nb containing TiAl alloy to an isothermal high-temperature heat treatment

Microstructure and tensile properties of hot fogred high Nb containing TiAl based alloy with initial near lamellar microstructure

“…This difference could be due to the high HIP temperature in αþγ phase field that improves the diffusion of β-stabilizing elements, namely, Nb and W. As shown in Fig. 1, the alloy contain more α 2 phases and thicker lamella spacing than that of traditional high Nb containing TiAl alloy, which reduces the blocking of interface to dislocation movement and is in favor of dynamic recrystallization (DRX) of coarsening γ laths [10,[17][18][19][20][21][22][23].…”

“…The yield stress is the highest when the loading axis is perpendicular to lamellar boundaries. In this direction, the α 2 phase is deformed in its hardest slip mode, and deformation must propagate through the lamellar interfaces, then this lamellar colony is in its hard orientation and will be remnant as RL structure [3][4][5][6][7][8][9][10][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Thus, the α 2 phase significantly affects the RL structure.…”

“…Zhang reported that the dislocation density in fine γ laths is considerable lower than that in coarse laths, and the extent of deformation and recrystallization of relatively coarse γ laths is higher than that of fine γ lath [22]. Moreover, the stacking fault energy of α 2 phase is higher than that of γ phase [10,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. At this point, the α phase tends to undergo dynamic recovery (DRV) during deformation in the αþγ phase field, whereas DRX is the main deformation mechanism of the γ phase.…”

A Combined Electromagnetic Levitation Melting, Counter‐Gravity Casting, and Mold Preheating Furnace for Producing TiAl Alloy

“…Hence, cracking and geometry distortion can be decreased to a large extent or even eliminated completely. Additionally, TiAl alloy with thin‐walls experiences a relatively fast cooling rate, which may result in quick solidification and even β‐microsegregation . Temperature‐controlled cooling is a desirable post‐processing method so that, the cooling rate and the isothermal temperature of TiAl castings are controlled.…”

A Two‐Step Heat Treatment to Eliminate the Micro‐Segregation of Ti–45Al–8.5Nb–0.2W–0.2B–0.02Y Alloy

“…[6,[24][25][26] Figure 6 shows the lamellar colony size distribution of VIM alloy in the cast condition and after HT#6, in which the discrete points represent experimental results and the lines represent the fitting results. a transformation occurs following the Burgers orientation relationship: (0001) a // {110} b and <11 20> a // <1 11> b .…”