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To investigate the effect of solidification parameters on the solidification path and microstructure evolution of Ti-45Al-5Nb(at.%) alloy, Bridgman-type directional solidification and thermodynamics calculations were performed on the alloy. The microstructures, micro-segregation and solidification path were investigated.The results show that the β phase is the primary phase of the alloy at growth rates of 5-20 μm·s~(-1) under the temperature gradients of 15-20 K·mm~(-1), and the primary phase is transformed into an α phase at relatively higher growth rates(V >20 μm·s~(-1)). The mainly S-segregation and β-segregation can be observed in Ti-45Al-5Nb alloy at a growth rate of 10 μm·s~(-1) under a temperature gradient of 15 K·mm~(-1). The increase of temperature gradient to 20 K·mm~(-1) can eliminate β-segregation, but has no obvious effect on S-segregation. The results also show that 5 at.% Nb addition can expand the β phase region, increase the melting point of the alloy and induce the solidification path to become complicated. The equilibrium solidification path of Ti-45Al-5Nb alloy can be described as L L→β L+β L+β→αα+β_R β→ααα→γα+γα→α_2+γγ_R+(α_2+γ), in which β_R and γ_R mean the residual β and γ
To investigate the effect of solidification parameters on the solidification path and microstructure evolution of Ti-45Al-5Nb (at.%) Alloy, Bridgman-type directional solidification and thermodynamics calculations were performed on the alloy. The microstructures, micro-segregation and solidification path were investigated. The results show that the β phase is the primary phase of the alloy at growth rates of 5-20 μm · s -1 under the temperature gradients of 15-20 K · mm -1, and The primary S-segregation and β-segregation can be observed in Ti-45Al-5Nb alloy at a growth (V> 20 μm · s -1) The increase of temperature gradient to 20 K · mm -1 can eliminate β-segregation, but has no obvious effect on S-segregation. The results also show that 5 at.% Nb addition can expand the β phase region, increase the melting point of the alloy and The equilibrium solidification path of the Ti-45Al-5Nb alloy can be described as LL → β L + β L + β → αα + β_R β → ααα → γα + γα → α_2 + γγ_R + (α_2 + γ), in which β_R and γ_R mean the residual β and γ