- 期刊
Fe_(83)B_(17)與Fe_(78)B_(13)Si_9合金之黏度及非晶態形成能力之研究
Viscosity and Glass Forming Ability of Fe_(83)B_(17) Alloy and Fe_(78)B_(13)Si_9 Alloys
摘要
本研究以旋轉式高溫黏度計量測Fe_(83)B_(17)與Fe_(78)B_(13)Si_9合金在液態溫度時之黏度變化，其關係可用Arrhenius方程式說明，但當溫度延伸到凝固點以下之過冷溫度範圍時，為了滿足合金在玻璃轉換溫度時其黏度趨於10^(13) Poise之急劇變化，本研究以自由體積理論模式推導該合金在過冷溫度範圍之黏度變化，求得合金在整個快速凝固過程中黏度與溫度變化之關係式，以提供理論模擬分析與製程控制所需之數據。同時，為了探討合金形成非晶態的能力，本研究由上述黏度變化之關係式，根據晶體均勻凝核與成長理論，計算合金在凝固過程中之恒溫變態T-T-T曲線，求得合金形成非晶態之臨界冷却速率。以此方法，計算Fe_(83)B_(17)與Fe_(78)B_(13)Si_9合金形成非晶態之臨界冷却速率分別為8.2* 10^5 ℃/sec與1.1* 10^5℃/sec,
關鍵字
無資料並列摘要
Using a rotational viscometer, the viscosity of molten Fe_(83)B_(17) and Fe_(78)B_(13)Si_9, alloys is measured. The temperature dependence of viscosity of the liquid alloy is represented by the Arrhenius relation. However, this expression cannot adequately describe the viscosity-temperature behavior for undercooled liquid. In this paper, it is assumed that the viscosity is 10^(13) Poise at the glass transition temperature, and from the liquid viscosity data, the viscosity of undercooled liquid is extrapolated by using free volume theory. These equations can be applied to model analysis and process control of rapid solidification process. Using these results, the isothermal T-T-T curves for crystallization are constructed based on the mechanism of homogeneous nucleation and crystal growth. From such curves, the critical cooling rate required to form glasses of Fe_(83)B_(17) and Fe_(78)B_(13)Si_9 alloys are found to be 8.2 * 10^5 ℃/sec and 1.1 * 10^5 ℃/ sec, respectively.