To go into detail, we are listing the proposals and speculations as put forward in our publications.
(1) The formation of cementite nanowires could be facilitated by impurities analogously to the mechanism proposed by Verhoeven, Pendray et al (1998) {Kochmann et al. 2004}
(2) Following a proposal of Pitsch et al., cementite might precipitate at (edge) dislocations in ferrite, which are attracting carbon. Since dislocation lines prefer certain lattice directions and slip planes, an orientation preference may occur. Moreover, impurity elements may facilitate both the nucleation (in particular V [Verhoeven et al] ) and the growth kinetics [Gosh et al] {Levin et al. 2005}.
(3) Given that the growth of carbon nanotubes from hydrocarbons inside micropores is facilitated by certain trace elements [Chernozatonski et al] , nanotubes in turn should initiate the formation of cementite nanowires and coarse cementite particles. This was already presumed by Verhoeven (2002) who thought that submicroscopic particles (possibly carbides and others) or defects could have served as preferred nucleation sites for the large cementite particles.
Moreover, we speculated that organic ingredients of ancient Indian wootz served as supplier of those hydrocarbons {Reibold, Paufler et al. 2006}.
(4) We observed colonies of straight parallel wires or elongated particles in one region along with colonies of curved wires which changed their shape by shear on the macroscopic (010) slip (or stacking fault) plane of cementite in another region of the blade. The question whether or not the cementite wires, which we recorded, existed prior to forging could not be resolved unambiguously. A bainite reaction could ensure the formation of those nanostructures during the process of plastic deformation. But we have no direct evidence for that. The various models (1)-(4), which we are using as working hypotheses, gained some plausibility over the past 5 years of our TEM work mainly by results of other authors. {Reibold et al. 2009}.
(5) Our own facilities to diversify the state of the specimens were limited. What we did was thermal treatment of a Damascene sabre {Reibold, Levin et al. 2006} and inspection of other wootz type steels, either historic or recent {Reibold et al. 2009}. Measurements of nano-hardness {Paetzke et al. 2010} support the idea quantitatively that it arises due to fibre strengthening by nanowires and -tubes {Reibold et al 2009}.
Read more of this discussion of nanotechnology in Damascene steel swords.
- Damascus Steel, the original article
- Nanoscale Precipitation in Genuine Wootz Steel Blades , comment by Madeleine Durand-Charre
References
W. Kochmann, M. Reibold, R. Goldberg, W. Hauffe, A.A. Levin, D.C. Meyer, Th. Stephan, H. Müller, A. Belger, P. Paufler: Nanowires in ancient Damascus steel. Journ.Alloys Compounds 372(2004)L15-L19
A.A. Levin, D.C. Meyer, M. Reibold, W. Kochmann, N. Pätzke, P. Paufler: Microstructure of a genuine Damascus sabre. Cryst. Res. Technol. 40(2005) 905 - 916
N. Paetzke, I.P. Shakhverdova, A.A. Levin, M. Reibold, W. Kochmann, P. Paufler, D.C. Meyer: Nanoindentation behaviour and microstructure of several wootz-type steels. Journ. Metallurgy Mater.Sci. 52(1)(2010)47-65
J. Piaskowski: Metallographic examination of two Damascene steel blades. J. Hist. Arabic Sci. 2(1978)3-30
W. Pitsch, A. Schrader: Archiv f. d. Eisenhüttenwesen 29, 715 (1958).
M. Reibold, P. Paufler, A.A. Levin, W. Kochmann, N. Pätzke, D.C. Meyer: Carbon nanotubes in an ancient Damascus sabre. Nature 444,16 November 2006,286
M. Reibold, N. Paetzke, A.A. Levin, W. Kochmann, I.P. Shakhverdova, P. Paufler, D.C. Meyer: Structure of several historic blades at nanoscale. Cryst. Res. Technol. 44(2009)1139 - 1146
M. Reibold, A.A. Levin, D.C. Meyer, P. Paufler, W. Kochmann: Microstructure of a Damascene sabre after annealing. Int.J.Mater.Res. 97(2006)1172-1182
J.D. Verhoeven, A.H. Pendray, W.E. Dauksch: The key role of impurities in ancient Damascus steel blades. JOM 50(1998)58-64
J.D. Verhoeven, E.D. Gibson: The divorced eutectoid transformation in steel. Metallurg. and Materials Trans. 29A(1998)1181-1189
J.D. Verhoeven: Genuine Damascus steel: a type of banded microstructure in hypereutectic steels. Steel Research 73(2002)356-365
B. Zschokke: Du Damassé et des lames de damas. Rev. Mét. Part I, 21(1924)635-669
- Prof.(i.R.)Dr.rer.nat.habil.Dr.h.c. Peter Paufler
- IUCr Book Review Editor Institut für Strukturphysik Technische Universitaet Dresden
- D-01062 Dresden
- Germany
