Evolution of the ωo phase in a β-stabilized multi-phase TiAl alloy and its effect on hardness

Fundamental and Application‐Oriented Research on Gamma Alloys

“…It will b e shown below t h a t t h e site occupations a n d a t o m i c i n t e r a c t i o n s discussed in t h e previous section are crucial t o t h e u n d e r s t a n d i n g of t h e lattice a n d sublattice c o r r e s p o n d e n c e as well as t h e p a t h s of m e t a s t a b l e p h a s e t r a n s f o r m a t i o n s t h a t occur in t h e Po phase. [20]) a n d h a s a very low solubility in t h e wo p h a s e [24]. Figure 3 shows t h e variation of e n e r g y along t h e j3o -> w " t r a n s f o rm a t i o n p a t h , depicted by t h e degree of collapse of layers 2, 3 a n d 5, 6 in F i g u r e 2(c), for N b -a n d M o -c o n t a i n i n g alloys [25].…”

Dependency of microstructure and microhardness on withdrawal rate of Ti-43Al-2Cr-2Nb alloy prepared by electromagnetic cold crucible directional solidification

“…1(d) and (e). Previous studies have proved that columnar grains inclined to the longitudinal axis under a higher withdrawal rate, and grains growth was easily disturbed [16] . So, to obtain continuous columnar grains, applying a slow withdrawal rate is highly necessary and desirable for CCDS processing.…”

“…The variation of HV was mainly attributed to the change of phases and interlamellar spacing. Firstly, as reported in references [16,17], B2 phase and α 2 phase are harder than the γ phase. In this case, increase of B2 phase and α 2 phase would result in the increase of Vickers microhardness of CCDS Ti-43Al-2Cr-2Nb alloy.…”

Precipitation Behavior of ωo Phase in Ti-37.5Al-12.5Nb Alloy

“…Meanwhile, Nb is a β phase stabilizer that extends the β phase field and facilitates the ordered ω (ω o ) phase transitions in the β o phase in high Nb-TiAl alloys [6][7][8][9]. Numerous studies have reported the ω o phase transformations in high Nb-TiAl alloys, indicating that the ω o phase is stable at 700-900 • C [10,11]. However, these studies have mainly focused on the transition process between the β o and ω o phases [6][7][8][9][10][11][12][13] or the α 2 to β o phase [14][15][16].…”

“…Numerous studies have reported the ω o phase transformations in high Nb-TiAl alloys, indicating that the ω o phase is stable at 700-900 • C [10,11]. However, these studies have mainly focused on the transition process between the β o and ω o phases [6][7][8][9][10][11][12][13] or the α 2 to β o phase [14][15][16]. Recently, some reports concentrated on the precipitation of the ω o phase in α 2 laths during aging and studied the relationship between the α 2 and ω o phases [10,[17][18][19][20].…”