Wei GUO
,
Yaping ZONG
,
Gang WANG
,
Liang ZUO
材料科学技术（英）
The effects of applied tensile strain on the coherent α2 →O-phase transformation in Ti-Al-Nb alloys are explored by computer simulation using a phase-field method. The focus is on the influence of the applied strain direction on the microstructure and volume fraction of the O-phase precipitates. It is found that altering applied strain direction can modify microstructure of Ti-25Al-10~12Nb (at.~pct) alloy duringα2 →O-phase transformation effectively and full laminate microstructure in the Ti-25Al-10Nb (at. pct) alloy can be realized by an applied strain only along the direction 30° away from theα2 phase <10 0> in magnitude equivalent to the stress-free transformation strain. The simulation also shows that not only the magnitude of applied strain but also the applied strain direction influences the O-phase volume fraction and the effect of strain direction on the volume fraction is up to 25%.
关键词:
Phase field simulation
,
null
,
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Juntao LI
,
Yaping ZONG
,
Shiming HAO
材料科学技术（英）
The α(α2)/γ phase equilibria in Ti-Al-X (X = C, B, Fe, Si in at. pct) ternary systems were studied by equilibrium heat-treatment and EPMA. The results show that the addition of B to the Ti-Al binary system leads to a shift of both α(α2)/[ α(α2)+γ] and [α(α2)+γ]/γ phase boundaries to Al-rich side and 0.1 B addition decreases Tα by 18℃. The addition of C leads to a shift of [α(α2)+γ]/γ phase boundary to Al-rich side but the effect of 0.2 at.pct C addition on Tα is very slight. The addition of Fe results inα(α2)/ [α(α2)+γ] and [α(α2)+γ]/γ phase boundaries shifting to Ti-rich side and 1.0 Fe addition increases Tα by 90~110℃. The addition of Si leads to a shift of α(α2)/α(α2)/ [α(α2)+γ]} phase boundary to Ti-rich side and the 0.3 Si addition increases Tα by 80~110℃. The solubilities for C, B and Si in α(α2) phase are higher than those in the γ phase but the solubility for Fe in α(α2) phase is lower than that in γ phase.
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