The drawn copper wires have been analyzed by differential scanning calorimeter(DSC) and a new method, which uses DSC measurements to determine the Johnson-Mehl-Avrami-Kolmogorov(JMAK) exponent via introducing Arrheniu...The drawn copper wires have been analyzed by differential scanning calorimeter(DSC) and a new method, which uses DSC measurements to determine the Johnson-Mehl-Avrami-Kolmogorov(JMAK) exponent via introducing Arrhenius behavior and modifying the baseline of DSC curves, has been proposed. The results show that JMAK exponent and recrystallization activation energy of the drawn copper wires with a strain of 2.77 are about 2.39 and 125 k J/mol, respectively. The line linking the tangency points of DSC curve hypotenuse can be used as the baseline when calculating recrystallization fraction. The JMAK exponent obtained by the DSC method is in a good agreement with that obtained by microhardness measurements. Compared to traditional methods to measure the exponent, the proposed method is faster and less labor intensive.展开更多
Differential scanning calorimeter combined with flux(dehydrated B2O3) processing was used to realize and precisely measure the undercooling of germanium melts.The highest undercooling obtained in this way was 190 K.Re...Differential scanning calorimeter combined with flux(dehydrated B2O3) processing was used to realize and precisely measure the undercooling of germanium melts.The highest undercooling obtained in this way was 190 K.Relations between the undercooling and cooling rate or overheating tem-perature are analyzed respectively.The undercooling obtained is found to be increased with increasing of the cooling rate in the range from 5 to 40 K/min.At a given cooling rate,the undercooling reached is increased with the increasing of the overheating temperature of the melt,but tends to be constant at last.Crystallization of the undercooled germanium melt is investigated at the same time.It is clearly shown that,the higher the cooling rate,the shorter time is needed for crystallization.展开更多
基金Projects(51171135,51371132,51471123) supported by the National Natural Science Foundation of ChinaProjects(2012K07-08,2013KJXX-61) supported by Key Science and Technology Program of Shaanxi Province,ChinaProject(2013JC14) supported by the Education Department Foundation of Shaanxi Province,China
文摘The drawn copper wires have been analyzed by differential scanning calorimeter(DSC) and a new method, which uses DSC measurements to determine the Johnson-Mehl-Avrami-Kolmogorov(JMAK) exponent via introducing Arrhenius behavior and modifying the baseline of DSC curves, has been proposed. The results show that JMAK exponent and recrystallization activation energy of the drawn copper wires with a strain of 2.77 are about 2.39 and 125 k J/mol, respectively. The line linking the tangency points of DSC curve hypotenuse can be used as the baseline when calculating recrystallization fraction. The JMAK exponent obtained by the DSC method is in a good agreement with that obtained by microhardness measurements. Compared to traditional methods to measure the exponent, the proposed method is faster and less labor intensive.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50171059)by the Nature Science Foundation of Hebei Province,China(Grant No.503278).
文摘Differential scanning calorimeter combined with flux(dehydrated B2O3) processing was used to realize and precisely measure the undercooling of germanium melts.The highest undercooling obtained in this way was 190 K.Relations between the undercooling and cooling rate or overheating tem-perature are analyzed respectively.The undercooling obtained is found to be increased with increasing of the cooling rate in the range from 5 to 40 K/min.At a given cooling rate,the undercooling reached is increased with the increasing of the overheating temperature of the melt,but tends to be constant at last.Crystallization of the undercooled germanium melt is investigated at the same time.It is clearly shown that,the higher the cooling rate,the shorter time is needed for crystallization.
