用等离子体法制备的纳米晶体铁由XRD和SEM等方法测定其晶粒尺寸的平均值为87nm.用绝热量热方法在79～371K温区精确测定了其低温热容,测量结果比大晶粒Fe的热容值有明显的增强.在80～300 K温区之间增强热容为8%～14%.差示扫描量热(DSC)在高温区的研究结果则表明,纳米晶体Fe在400～700 K温区有一个宽的放热峰,对应于非平衡晶格缺陷所引起的焓释放850 K观察到一个放热峰.是纳米晶体铁从α相向α+γ相转变所引起的
The sample of nanocrystalline iron with the average grain size of 87nm was prepared by thermal plasma technique, and characterized by XRD and SEM. Measurement of low temperature heat capacity of the nano-Fe has been performed in the temperature range of 79～371K with an automated adiabatic calorimeter. Enhanced heat capacities varying from 8% to 14% were observed.The differential scanning calorimetric measurement showed one broad exothermic regime from 400K to700K corresponding to the enthalpy releasing, due to the contribution of nonequibrium lattice defects.An endothermic peak at 850K due to a γ→α + γ phase transition of nc-Fe was observed.
参考文献
| [1] | H.Gletiter, Prog. Mater. Sci., 33, 223(1989) |
| [2] | J.Rupp, R.Birringer, Phys. Rev., B36, 7888(1987) |
| [3] | D.Korn, A.Morsch, R.Birringer, W.Arnold, H.Glerter, J.Appl. Phys., 49, C5～769(1988) |
| [4] | E.Hellstern, H.J.Fecht, Z.Fu, W.L.Johnson, J.Appl. Phys., 65, 305(1989) |
| [5] | K.Lu, J.T.Wang, W.D.Wei, Scr. Metall. Mater., 25, 619(1991) |
| [6] | Y.Y.Chen, Y.D.Yao, S.S.Hsiao, S.U.Jen, B.T.Lin, H.M.Lin, C.Y.Tung, Phys. Rew., B52, 9364(1995) |
| [7] | M.Wanger, Phys. Rev. B45, 635(1992) |
| [8] | H.Y.Bai, J.L.Luo, D.Jin, J.R.Sun, J.Appl.Phys., 79, 361(1996) |
| [9] | Z.C.Tan, G.Y.Sun, Y.Sun, J.Thermal Analysis, 45, 59(1995) |
| [10] | D.A.Ditmars, S.Ishihara, S.S.Chang, G.Bernstein, E.D.West, J.Res.Natl. Bur. Stand., 87, 159(1982) |
| [11] | L.S.Birks, H.Friedamn, J.Appl. Phys., 17, 687(1946) |
| [12] | K.K.Kelly, J.Chem. Phys., 11, 16(1943) |
| [13] | a. Révész, J.Lendvai, Nanostructured Materials, 10, 13(1998) |
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