The eutectoid transition in the iron-carbon system around 730 degrees C has been tested as a potential fixed point for use in thermocouple thermometry. Using a heating rate <= 1.5 C min(-1), the alpha-gamma transition showed a short, but repeatable, plateau with a repeatability of 0.07 degrees C. However, the gamma-alpha transition only exhibited a small discontinuity in a plot of emf versus time. Although only preliminary results were obtained here, once the thermodynamic (or the ITS-90) temperature, as well as its uncertainty, is assigned to this eutectoid transition, then the hypereutectoid transition in the iron-carbon system is potentially very useful, in that this fixed point can be obtained additionally while realizing the iron-carbon eutectic point.
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机译：铁碳系统中约730摄氏度的共析转变已作为热电偶测温的潜在固定点进行了测试。使用加热速率<= 1.5 C min（-1），α-γ跃迁显示出短暂但可重复的平稳期，重复性为0.07℃。但是，γ-α跃迁在图中仅表现出较小的不连续性电动势与时间的关系。尽管此处仅获得了初步的结果，但是一旦将热力学（或ITS-90）温度及其不确定性分配给该共析转变，那么铁碳体系中的超共析转变可能非常有用，因为在实现铁碳共晶点的同时，可以额外获得该固定点。
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