ISOTHERMAL CRYSTALLIZATION KINETICS OF NI24ZR76 AND NI24(ZR-X)76 AMORPHOUS-ALLOYS
ISOTHERMAL CRYSTALLIZATION KINETICS OF NI24ZR76 AND NI24(ZR-X)76 AMORPHOUS-ALLOYS
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DOI：
10.1016/0956-7151(91)90292-9
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发表时间：
1991-05-01
期刊：
影响因子：
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通讯作者：
DELAEY, L
中科院分区：
文献类型：
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作者：
GHOSH, G;CHANDRASEKARAN, M;DELAEY, L
采用DSC、光学显微镜、透射电镜和x射线衍射等手段研究了熔纺Ni24Zr76和Ni24(Zr-X)76非晶合金的等温反硝化动力学。这些非晶合金表现出共晶结晶。DSC得到的等温反硝化动力学根据Kolmogorov-Johnson-Mehl-Avrami （KJMA）模型进行了分析。经典的KJMA图从转换开始就表现出明显的非线性。这种非线性可归因于许多因素，如表面诱导结晶、晶体的各向异性生长、碰撞效应（硬和软）以及脱氮过程中成核速率的变化等。在这些合金中，稳态成核频率是在一个明确定义的瞬态时期后建立的。用非稳态成核理论对瞬态时间进行了定量分析，发现理论估计的瞬态时间与实验观察到的潜伏期一致。应用经典的均形核理论，发现在不发生非均形核的情况下，淬火核的密度很小。
Isothermal devitrification kinetics of the melt-spun Ni24Zr76 and Ni24(Zr-X)76 amorphous alloys has been studied by means of DSC, optical microscopy, TEM and X-ray diffraction. These amorphous alloys exhibit eutectic crystallization. Isothermal devitrification kinetics, as obtained by DSC, has been analyzed in terms of Kolmogorov-Johnson-Mehl-Avrami (KJMA) model. The classical KJMA plots exhibit significant non-linearity from the beginning of the transformation. Such non-linearity has been attributed to a number of factors such as surface-induced crystallization, anisotropic growth of crystals, impingement effects (hard and soft) and variation of the nucleation rate during devitrification etc. In these alloys, the steady state nucleation frequency is established after a well-defined transient period. A quantitative analysis of the transient period has been performed in terms of non-steady state nucleation theory and the theoretically estimated transient times are found to be consistent with the experimentally observed incubation periods. By applying classical theory of homogeneous nucleation, it is found that the density of quenched-in nuclei will be very small in the absence of heterogeneous nucleation.