1. Department of Information Engineering, Gannan Medical University, Jiangxi Province Ganzhou 341000, China; 2. School of Physics and Microelectronics Science, Hunan University, Hunan Province Changsha 410082, China
Abstract：The molecular dynamics simulation calculation on the microclusters evolution properties of liquid Mg3Ca7 during the rapid solidifications has been performed. Results indicated that the icosahedron microcluster played key role in the glass transition which happened at about 600 K; it suggests that the formation and evolution mechanism of icosahedral order is important for the corrosion resistance of medical implant material of Mg- and Mg-Ca based alloys. It is also found that the icosahedron structure is unstable in the liquid and supercooled liquid until the glass transition occurs.
[1] Li ZJ, Gu XN, Lou SQ, et al.The development of binary Mg-Ca alloys for use as biodegradable materials within bone[J].Biomaterial, 2008, 29(10):1329-1344. [2] Xie X, Wang X, Wang Y, et al.Ca-Mg-Zn metallic glass as degradable biomaterials developed for potential orthopaedic applications[J].Bone,2010, 47:S425. [3] Xu L, Pan F, Yu G, et al.In vitro and in vivo evaluation of the surface bioactivity of a calcium phosphate coated magnesium alloy[J].Biomaterial,2009, 30(8):1512-1523. [4] Gu XN, Li N, Zhou WR, et al.Corrosion resistance and surface biocompatibility of a microarc oxidation coating on a Mg-Ca alloy. Acta[J]. Biomaterial, 2011,7(4):1880-1889. [5] Wang S, Lai SK.Structure and electrical resistivities of liquid binary alloys[J]. Journal of Physics F: Metal Physics,1980, 10(12):2717-2737. [6] Li DH, Li XR, Wang S.Variational calculation of Helmholtz free energies with applications to the sp-type liquid metals[J]. Journal of Physics F: Metal Physics, 2000, 16(3):309-321. [7] Hoover WG, Ladd AJC, Moran B.High-strain-rate plastic flow studied via nonequilibrium molecular dynamics[J]. Physical Review Letters,1982, 48(26):1818-1820. [8] Evans DJ.Computer "experiment" for nonlinear thermodynamics of Couette flow[J]. The Journal of Chemical Physics,1983, 78:3297-3302. [9] Hou ZY, Liu RS, Liu HR, et al.Formation mechanism of critical nucleus during nucleation process of liquid metal sodium[J]. The Journal of Chemical Physics, 2007, 127(17):174503-174509. [10] Zhou LL, Liu RS, Tian ZA, et al.Kinetic details of crystallization in supercooled liquid Pb during the isothermal relaxation[J]. Journal of Physics: Condensed Matter, 2012,407:240-245. [11] Liu FX, Liu RS, Hou ZY, et al.Formation mechanism of atomic cluster structures in Al-Mg alloy during rapid solidification processes[J]. Annals of Physics, 2009, 324(2):332-342. [12] Jaswal SS, Hafner J.Atomic and electronic structure of crystalline and amorphous alloys. I. Calcium-magnesium compounds[J]. Physical Review B, 1988,38(11):7311-7319. [13] Vollmayr K, Kob W, Binder K.Cooling-rate effects in amorphous silica: A computer-simulation study[J]. Physical Review B, 1996, 54(22):15808. [14] Wendt HR, Abraham FF.Empirical criterion for the glass transition region based on monte carlo simulations[J]. Physical Review Letters, 1978, 41(18):1244-1246. [15] Zeng R, Dietzel W, Witte F, et al.Progress and challenge for magnesium alloys as biomaterials[J]. Advanced Engineering Materials, 2008,10(8):B3-B14. [16] Witte F, Kaese V, Haferkamp H, et al.In vivo corrosion of four magnesium alloys and the associated bone response[J]. Biomaterial, 2005,26(17):3557-3563. [17] Honeycutt JD, Anderson. HC.Small system size artifacts in the molecular dynamics simulation of homogeneous crystal nucleation in supercooled atomic liquids[J]. The Journal of Chemical Physics,1986,90(8):1585-1589.
