Experimental study of the dissolution and reprecipitation behaviors of ωo phase in high Nb containing TiAl alloy
Experimental study of the dissolution and reprecipitation behaviors of ωo phase in high Nb containing TiAl alloy
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DOI：
10.1016/j.matchar.2015.09.028
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发表时间：
2015-11
影响因子：
4.7
通讯作者：
B. Tang;W. Ou;H. Kou;Jinshan Li
中科院分区：
文献类型：
--
作者：
B. Tang;W. Ou;H. Kou;Jinshan Li
研究了标称成分为Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y （at.%）的铸态高铌TiAl合金在等温退火和700 ~ 800℃再时效过程中ω相的溶解和再析出行为。显微组织表征表明，铸态合金中有序β相中存在大量微米级ω粒子。这些ω粒子在800℃和850℃退火100 h时具有较高的热稳定性，当温度升高到900℃时，ω粒子开始分解为β相，相变速率较低。进一步升高温度会加速ω相的溶解动力学。随后在700℃下再时效和随后的淬火导致纳米ω粒子的再析出，并伴有极细的γ板。当时效温度提高到800℃时，微米级ω粒子从β相析出，并伴有粗化的γ板。讨论了ω相再析出行为的可能机理。
The dissolution and reprecipitation behaviors of ωophase during isothermal annealing and ensuing re-aging at 700–800 °C are investigated on an as-cast high Nb containing TiAl alloy with nominal composition of Ti–45Al–8.5Nb–0.2W–0.2B–0.02Y (at.%). The microstructural characterization revealed that numerous micron-sized ωoparticles exist within the ordered βophase in the as-cast alloy. These ωoparticles have high thermal stability when annealing at 800 °C and 850 °C for 100 h. Increasing the temperature to 900 °C, the ωoparticles began to decompose into βophase with a low transformation rate. Further increasing temperature causes accelerated dissolution kinetics of ωophase. Ensuing re-aging at 700 °C and subsequent quenching lead to the reprecipitation of nano-sized ωoparticles accompanied by extremely fine γ plates. When the aging temperature increases to 800 °C, the micron-sized ωoparticles precipitate from βophase accompanied by coarsened γ plates. Possible mechanism of the reprecipitation behavior of ωophase is discussed.