Crystallization kinetics of some iron-based metallic glasses

Time-resolved synchrotron x-ray diffraction studies of the crystallization of amorphous Co(80−x)FexB20

“…It should be noted that because Fe and Co are almost completely indistinguishable by x-rays a 50-50% occupation was assumed and site occupancies were kept constant. Typically in iron metalloid glasses, phase formation progresses with a primary phase formation of α-Fe [11][12][13] , while in CoFeB alloys Co and Fe atoms form continuous solid solutions in the α-Fe phase to form α-(Co,Fe) 14 . 16 , and therefore a deviation in the lattice parameter from α-Fe is likely to be associated with an increase of Co content.…”

“…For example, in Fe 65 Co 18 B 16 Si 1 n was calculated as 1.6 26 , and in (Co,Fe) 89 (MnMoSiB) 81 n = 1.48 27 , although neither reference specifies which crystal phase n was calculated for. In general the growth of α-Fe is reported to be diffusion controlled 11,12,28 , in which case an Avrami exponent between 1.5 and 2.5 suggests that all crystals grow from small dimensions with a decreasing nucleation rate 24 .…”

Thermal Stability of the Nanostructured Powder Mixtures Prepared by Mechanical Alloying

“…Calka and Radlinski [32] have shown that the usual method of applying the Kolmogorov-Johnson-Mehl-Avrami equation and calculating the mean value of Avrami exponent over a range of volume fraction transformed, may be inappropriate, even misleading, if competing reactions or changes in growth dimensionality occur during the transformation progress. Also, a close examination of the Avrami plots reveals that there are deviations from linearity over the full range of volume fraction transformed [33]. The first derivative of the Avrami plot ln −ln 1− ln ⁄ against the volume fraction transformed [34], which effectively gives the local value of with , seems to be more sensitive.…”

A Solid-State NMR Study of Coordination Transformation in Amorphous Aluminum Oxide: Implication for Crystallization of Magma Ocean

“…결정화 과정의 반응속도를 정립하기 위하여, 광 학현미경이나 주사전자현미경(Scanning electron microscope, SEM) 이미지를 관찰하여 직접 형성 된 결정의 개수를 세는(modal counting) 분석법이 이용되기도 하였고(e.g., James, 1974), 시차주사 열량측정법(Differential scanning calorimetry, DSC)이나 시차열분석법(Differential thermal analysis, DTA)으로 결정화 반응 시 발생하는 열량변화 를 통해 결정화 온도나 속도를 규명하였다(e.g., Kissinger, 1957;Gibson and Delamore, 1987). 또 한 투과전자현미경(Transmission electron microscope, TEM)의 전자회절패턴이나 X선 회절분석(Xray diffraction)을 통해서 결정의 형성여부를 파악 하여 결정화 속도에 대한 정보를 획득하기도 하였 다(e.g., Zhang and Banfield, 2002 Na와 같 은 핵종) 주변의 원자 환경에 관한 정량적인 정보 를 제공한다 (Lee, 2005).…”