The Deformation and Dynamic Recrystallization in a Hot Isostatically Pressed Ti-48Al-2W Powder Alloy
- PDF / 4,462,320 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 109 Downloads / 226 Views
THE DEFORMATION AND DYNAMIC RECRYSTALLIZATION IN A HOT ISOSTATICALLY PRESSED Ti-48AI-2W POWDER ALLOY L. ZHAO*, J. BEDDOESt and W. WALLACE* " Structures and Materials Laboratory, Institute for Aerospace Research, National Research Council Canada, Ottawa, Canada t Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Canada
ABSTRACT Titanium aluminide powder of composition Ti-48A1-2W (at%) was consolidated by hot isostatic pressing (HIP) at 200 MPa and 1050'C, 11000 C, 1 150'C and 1250'C, respectively. The as-HIP'ed microstructure and substructure were characterized by optical microscopy and transmission electron microscopy (TEM). The densified powder alloy possesses an inhomogeneous microstructure consisting of fine-grained prior dendrites and coarse-grained interdendritic regions. The former contain the y, %2 and P3. phases. The HIP processing induced substantial deformation in the latter regions where dislocation segments and tangles, deformation twins and dislocation sub-boundaries were formed, indicative of plastic yielding and creep deformation. Both 1/2, y+(2+po. TEM experiments also revealed that the consolidated prior dendrites had a low dislocation density. The dislocations present are predominantly in the y phase, which is the softest phase [9]. Diffraction experiments showed that the interdendritic areas consist predominantly 2.2 11.0 of y phase. Figure 6 illustrates the i-48AI-2W Powder As-HP13'ed 1000Dendrite Area Fractgon 2. interdendritic structure with both recrystallized and non-recrystallized regions - 0- Dendrite Grain Size .10 distinguishable. In the latter region, ILi ,8.0 1.2 irregularly shaped coarse grains contain a 0 high density of dislocation segments and 0.8 :
_7.0
C
.
1050
1.0
1100
115
1150
,
1200
0 1250
HIP Temperature (-C)
tangles,
with deformation twins and
c. dislocation sub-boundaries. Diffraction contrast experiments revealed that both
1/2
Data Loading...
