Formation and Thermal Stability of ω-Ti(Fe) in α-Phase-Based Ti(Fe) Alloys
Formation and Thermal Stability of ω-Ti(Fe) in α-Phase-Based Ti(Fe) Alloys
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DOI：
10.3390/met10030402
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发表时间：
2020-03-01
期刊：
影响因子：
2.9
通讯作者：
Rafaja, David
中科院分区：
文献类型：
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作者：
Kriegel, Mario J.;Rudolph, Martin;Rafaja, David
本工作研究了含2 wt.% α-Ti + TiFe两相合金中高压扭转（HPT）产生的ω-Ti（Fe）相的形成和热稳定性，4重量%和10重量%铁.两相组织是通过在470 ℃下退火4000 h，然后在水中淬火来实现的。利用扫描电子显微镜（SEM）和X射线衍射（XRD）对样品进行了表征。利用差示扫描量热法（DSC）和原位高温XRD研究了ω-Ti（Fe）相的热稳定性。在HPT过程中，高压ω-Ti（Fe）相主要由α-Ti形成。它在130摄氏度的温度下通过一系列放热反应开始分解。分解在类似于320 ℃以上完成。在进一步加热时，通过形成过饱和的α-Ti（Fe）相进行相变。最后，在高温下建立了平衡相组合。在变形和热处理的样品中测量的共析温度和相变温度进行比较，对于具有不同铁浓度的样品和对于具有不同相组成的样品，在HPT过程之前。进行热力学计算以预测低温（α-Ti + TiFe）和高温（α-Ti + β-（Ti，Fe），β-（Ti，Fe））热处理后的稳定和亚稳相组合。
In this work, the formation and thermal stability of the omega-Ti(Fe) phase that were produced by the high-pressure torsion (HPT) were studied in two-phase alpha-Ti + TiFe alloys containing 2 wt.%, 4 wt.% and 10 wt.% iron. The two-phase microstructure was achieved by annealing the alloys at 470 degrees C for 4000 h and then quenching them in water. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were utilized to characterize the samples. The thermal stability of the omega-Ti(Fe) phase was investigated using differential scanning calorimetry (DSC) and in situ high-temperature XRD. In the HPT process, the high-pressure omega-Ti(Fe) phase mainly formed from alpha-Ti. It started to decompose by a cascade of exothermic reactions already at temperatures of 130 degrees C. The decomposition was finished above similar to 320 degrees C. Upon further heating, the phase transformation proceeded via the formation of a supersaturated alpha-Ti(Fe) phase. Finally, the equilibrium phase assemblage was established at high temperatures. The eutectoid temperature and the phase transition temperatures measured in deformed and heat-treated samples are compared for the samples with different iron concentrations and for samples with different phase compositions prior to the HPT process. Thermodynamic calculations were carried out to predict stable and metastable phase assemblages after heat-treatments at low (alpha-Ti + TiFe) and high temperatures (alpha-Ti + beta-(Ti,Fe), beta-(Ti,Fe)).