Tag Archives: Peter Paufler

The relationship between Valyrian steel (from Game of Thrones), Damascus steel, and nuclear nanotechnology

There’s a very interesting June 20, 2014 posting by Charles Day on his Dayside blog (located on the Physics Today website). Day manages to relate the Game of Thrones tv series to nuclear power and nanotechnology,

The military technology of A Song of Ice and Fire, George R. R. Martin’s series of fantasy novels, is medieval with an admixture of the supernatural. Dragons aside, among the most prized weapons are swords made from Valyrian steel, which are lighter, stronger, and sharper than ordinary steel swords.

Like many of the features in the rich world of the novels and their TV adaptation, Game of Thrones, Valyrian steel has a historical inspiration. Sometime before 300 BC, metalworkers in Southern India discovered a way to make small cakes of high-carbon steel known as wootz. Thanks to black wavy bands of Fe3C particles that pervade the metal, wootz steel was already strong. …

Perhaps because the properties of wootz and Damascus steels depended, in part, on a particular kind of iron ore, the ability of metallurgists to make the alloys was lost sometime in the 18th century. In A Song of Ice and Fire, the plot plays out during an era in which making Valyrian steel is a long-lost art.

Martin’s knowledge of metallurgy is perhaps shaky. …

Interestingly, the comments on the blog posting largely concern themselves with whether George RR Martin knows anything about metallurgy. The consensus being that he does and that the problems in the Game of Thrones version of metallurgy lie with the series writers.

I first came across the Damascus steel, wootz, and carbon nanotube story in 2008 and provided a concise description on my Nanotech Mysteries wiki Middle Ages page,

Damascus steel blades were first made in the 8th century CE when they acquired a legendary status as unlike other blades they were able to cut through bone and stone while remaining sharp enough to cut a piece of silk. They were also flexible which meant they didn’t break off easily in a sword fight. The secret for making the blades died (history does not record how) about 1700 CE and there hasn’t been a new blade since.

 The blades were generally made from metal ingots prepared in India using special recipes which probably put just the right amount of carbon and other impurities into the iron. By following these recipes and following specific forging techniques craftsmen ended up making nanotubes … When these blades were nearly finished, blacksmiths would etch them with acid. This brought out the wavy light and dark lines that make Damascus swords easy to recognize.3

 It turns out part of the secret to the blade is nanotechnology. Scientists discovered this by looking at a Damascus steel blade from 1700 under an electron microscope. It seems those unknown smiths were somehow encasing cementite nanowires in carbon nanotubes then forging them into the steel blades giving them their legendary strength and flexibility.

The reference information I used then seems to be no longer available online but there is this more than acceptable alternative, a Sept. 27, 2008 postiing by Ed Yong from his Not Exactly Rocket Science blog (on ScienceBlogs.com; Note: A link has been removed),

In medieval times, crusading Christian knights cut a swathe through the Middle East in an attempt to reclaim Jerusalem from the Muslims. The Muslims in turn cut through the invaders using a very special type of sword, which quickly gained a mythical reputation among the Europeans. These ‘Damascus blades‘ were extraordinarily strong, but still flexible enough to bend from hilt to tip. And they were reputedly so sharp that they could cleave a silk scarf floating to the ground, just as readily as a knight’s body.

They were superlative weapons that gave the Muslims a great advantage, and their blacksmiths carefully guarded the secret to their manufacture. The secret eventually died out in the eighteenth century and no European smith was able to fully reproduce their method.

Two years ago, Marianne Reibold and colleagues from the University of Dresden uncovered the extraordinary secret of Damascus steel – carbon nanotubes. The smiths of old were inadvertently using nanotechnology.

Getting back to Day, he goes on to explain the Damascus/Valyrian steel connection to nuclear power (Note: Links have been removed),

Valyrian and Damascus steels were on my mind earlier this week when I attended a session at TechConnect World on the use of nanotechnology in the nuclear power industry.

Scott Anderson of Lockheed Martin gave the introductory talk. Before the Fukushima disaster, Anderson pointed out, the principal materials science challenge in the nuclear industry lay in extending the lifetime of fuel rods. Now the focus has shifted to accident-tolerant fuels and safer, more durable equipment.

Among the other speakers was MIT’s Ju Li, who described his group’s experiments with incorporating carbon nanotubes (CNTs) in aluminum to boost the metal’s resistance to radiation damage. In a reactor core, neutrons and other ionizing particles penetrate vessels, walls, and other structures, where they knock atoms off lattice sites. The cumulative effect of those displacements is to create voids and other defects that weaken the structures.

Li isn’t sure yet how the CNTs resist irradiation and toughen the aluminum, but at the end of his talk he recalled their appearance in another metal, steel.

In 2006 Peter Paufler of Dresden University of Technology and his collaborators used high-resolution transmission electron microscopy (TEM) to examine the physical and chemical microstructure of a sample of Damascus steel from the 17th century.

The saber from which the sample was taken was forged in Isfahan, Persia, by the famed blacksmith Assad Ullah. As part of their experiment, Paufler and his colleagues washed the sample in hydrochloric acid to remove Fe3C particles. A second look with TEM revealed the presence of CNTs.

There’s still active interest in researching Damascus steel blades as not all the secrets behind the blade’s extraordinary qualities have been revealed yet. There is a March 13, 2014 posting here which describes a research project where Chinese researchers are attempting (using computational software) to uncover the reason for the blade’s unique patterns,

It seems that while researchers were able to answer some questions about the blade’s qualities, researchers in China believe they may have answered the question about the blade’s unique patterns, from a March 12, 2014 news release on EurekAlert,

Blacksmiths and metallurgists in the West have been puzzled for centuries as to how the unique patterns on the famous Damascus steel blades were formed. Different mechanisms for the formation of the patterns and many methods for making the swords have been suggested and attempted, but none has produced blades with patterns matching those of the Damascus swords in the museums. The debate over the mechanism of formation of the Damascus patterns is still ongoing today. Using modern metallurgical computational software (Thermo-Calc, Stockholm, Sweden), Professor Haiwen Luo of the Central Iron and Steel Research Institute in Beijing, together with his collaborator, have analyzed the relevant published data relevant to the Damascus blades, and present a new explanation that is different from other proposed mechanisms.

At the time the researchers were hoping to have someone donate a piece of genuine Damascus steel blade. From my March 13, 2014 posting,

Note from the authors: It would be much appreciated if anyone would like to donate a piece of genuine Damascus blade for our research.

Corresponding Author:

LUO Haiwen
Email: haiwenluo@126.com

Perhaps researchers will manage to solve the puzzle of how medieval craftsman were once able to create extraordinary steel blades.

Ahoy me hearties! A new theory for Damascus steel

I hope I got that right. It’s been a long time since I’ve seen a pirate movie but talk of Damascus steel meant that I had to have at least one movie pirate-type phrase in this piece.

I first came across Damascus steel outside the pirate movie domain in 2007 about the time that researchers declared blades made of Damascus steel sported carbon nanotubes giving  the blades their legendary qualities. From a Nov. 16, 2006 National Geographic article by Mason Inman,

New studies of Damascus swords are revealing that the legendary blades contain nanowires, carbon nanotubes, and other extremely small, intricate structures that might explain their unique features.

Damascus swords, first made in the eighth century A.D., are renowned for their complex surface patterns and sharpness. According to legend, the blades can cut a piece of silk in half as it falls to the ground and maintain their edge after cleaving through stone, metal, or even other swords.

Now studies of the swords’ molecular structure are uncovering the tiny structures that may explain these properties.

Peter Paufler, a crystallographer at Technical University in Dresden, Germany, and his colleagues had previously found tiny nanowires and nanotubes when they used an electron microscope to examine samples from a Damascus blade made in the 17th century.

It seems that while researchers were able to answer some questions about the blade’s qualities, researchers in China believe they may have answered the question about the blade’s unique patterns, from a March 12, 2014 news release on EurekAlert,

Blacksmiths and metallurgists in the West have been puzzled for centuries as to how the unique patterns on the famous Damascus steel blades were formed. Different mechanisms for the formation of the patterns and many methods for making the swords have been suggested and attempted, but none has produced blades with patterns matching those of the Damascus swords in the museums. The debate over the mechanism of formation of the Damascus patterns is still ongoing today. Using modern metallurgical computational software (Thermo-Calc, Stockholm, Sweden), Professor Haiwen Luo of the Central Iron and Steel Research Institute in Beijing, together with his collaborator, have analyzed the relevant published data relevant to the Damascus blades, and present a new explanation that is different from other proposed mechanisms.

Before the development of tanks, guns, and cannons, humans fought with swords, and there was one type of sword in particular that everyone wanted, a Damascus sword. Western Europeans first encountered these swords in the hands of Muslim warriors in Damascus about a thousand years ago. Damascus swords were prized for their strength and sharpness. They were famous for being so sharp that they could cut a silk scarf in half as it fell to ground, something that European swords could not do. Both Mediterranean and European blacksmiths believed that the outstanding strength and sharpness of the swords resulted from their beauty, i.e., the Damascus pattern. This presents as a wavy pattern like a rose and ladder on the surface of Damascus blades, as shown in Fig. 1. It was recorded that blacksmiths in Persia made the best Damascus steel swords by hammering a small cake of Wootz steel, which was a high-quality steel ingot imported from ancient India. The best European blade smiths from the Middle Ages onwards were not able to fabricate similar blades, even though they carefully studied examples made in the East. Damascus blades became even more mysterious when the art of making them actually died out. Despite all the knowledge and technological advances of the 21st century, people are still debating the mechanism through which such beautiful patterns were formed on Damascus blades.

Here’s the figure showing a blade and its pattern,

Caption: This is an example of a Damascus sword with a typical Damascus pattern of Muhammad ladder and rose. Microstructural examination of the blade indicates that rows of cementite particles (in black) form the Damascus patterns[11]. Credit: ©Science China Press

Caption: This is an example of a Damascus sword with a typical Damascus pattern of Muhammad ladder and rose. Microstructural examination of the blade indicates that rows of cementite particles (in black) form the Damascus patterns[11].
Credit: ©Science China Press

The news release goes on,

The compositions and microstructures of many existing Damascus steel blades have been examined previously. Their C contents are within the range of 1 wt.%, and often around 1.6 wt.%. It is also known that the Damascus pattern results from the band-like formation of coarse cementite particles. The high C content leads to a large amount of cementite particles being precipitated during hot hammering. After proper etching, the coarse cementite bands appear white within the dark matrix, such that they form a visible pattern on the surface. After the 1970s, the mechanism for the formation of the Damascus pattern was revisited and debated, particularly by Professors Verhoeven from Iowa State University and Sherby from Stanford University. Sherby and his co-workers[1-4] thought that a coarse cementite network was formed around the large austenite grains, when the Wootz steel cake was cooled slowly in crucibles for several days after melting. Later, the continuous cementite network was broken into spheroidal particles during extensive hammering at relatively low temperatures between cherry (850 °C) and blood red (650 °C), rather than the white heat customarily used by European blacksmiths. Furthermore, Wootz steel cake must be used in the manufacture of genuine Damascus blades. The low-temperature hammering was also a key technology, by which Wootz steels were easily hot deformed without cracking, and finer carbide particles precipitated to make the steel stronger and tougher. However, Verhoeven et al. though that the Damascus pattern was related to the microsegregation of solutes during solidification. They carried out experiments on two genuine Damascus blades during which the carbides were removed completely by dissolution treatment, followed by quenching. It was shown that the planar arrays of carbide particles could be made to return, together with the surface pattern, by thermal cycling, whereas the Sherby mechanism requires the cementite particles formed on the boundaries of the large austenite grains to be retained during deformation. Hence, they argued strongly that the surface patterns formed on genuine Damascus steel blades should result from a type of microsegregation-induced carbide banding that requires thermal cycling[5-10]. In particular, the dendritic segregation of V was considered the most likely reason for carbide banding[11].

However, compositional examinations of some existing Damascus steel blades revealed that many of them contain almost no V or any other carbide-forming elements. Moreover, it is apparent that the ancient craftsmen making Wootz steels had no concept of alloying with particular elements such as V. As Wootz steel cakes have been discovered in many parts of the ancient Indian region, it is unlikely that the iron ores in all those places happened to contain V or other certain types of carbide-forming elements. Therefore, the explanation proposed by Verhoeven et al. is also less than convincing.

Luo et al. adopted a new method to approach this puzzle. Using an advanced metallurgical computational software package (Thermo-Calc), all possible factors, such as the influence of S, P, and V elements on the Fe-C phase diagram, precipitation of V(CN), diffusion of V in austenite, and the dendritic segregation of S and P during solidification were quantified, because they have all been considered as possible prerequisites for forming Damascus patterns. The calculations indicated that V(CN) particles precipitate or dissolve at temperatures much lower than cementite in cases with a low content of V, as is commonly found in Damascus steels (see Fig. 2a). Instead, the sulfide and phosphide could precipitate at the dendritic zone because of the severe segregation during slow solidification. In particular, the remaining P-rich liquid at the end of solidification might transform to a eutectic product of phosphide and cementite (Fig. 2b), which cannot be distinguished from cementite under an optical microscope. The high concentration of P will not be homogenized by diffusion after a short dissolution treatment, such that cementite might re-precipitate in the P-segregated regions. Therefore, the dendritic segregation of P influences the spatial distribution of cementite in Damascus blades and thus, the patterns are formed.

Luo et al. also suggested that their method could be widely employed to tackle other puzzles similar to that of the Damascus patterns, because today’s knowledge is so well developed that reliable theoretical computations are now possible. Although people were capable of making Damascus steel swords containing ultrahigh carbon contents (1 wt.%) a long time ago, it is surprising that almost all modern steels in use contain C contents below 1 wt.%. However, with future developments of knowledge and technology, it is expected that ultrahigh carbon steels. e.g., Wootz steels, will once again find important applications, because the best of the new is often the long-forgotten past.

I want to draw attention to two elements that distinguish this news release, the request from the authors and the bibliographic notes (I don’t recall seeing bibliographies appended to a news release before),

Note from the authors: It would be much appreciated if anyone would like to donate a piece of genuine Damascus blade for our research.

Corresponding Author:

LUO Haiwen
Email: haiwenluo@126.com

References

1. Sherby O D, Wadsworth J. Damascus Steels. Sci Amer, 1985,252:112-118

2. Wadsworth J, Sherby O D. On the Bulat Damascus steels revisited. Prog Mater Sci, 1980,25:35-68

3. Sherby O D, Wadsworth J. Ancient blacksmiths, the Iron Age, Damascus steels, and modern metallurgy. J of Mater Processing Techno, 2001,117:347-352

4. Wadsworth J, Sherby O D. Response to Verhoeven comments on Damascus steel. Mater Charact, 2001, 47: 163

5. Verhoeven J D, Pendary A H. Origin of the Damask pattern in Damascus steel blades. Mater Charact, 2001, 47: 423

6. Verhoeven J D, Pendary A H. On the origin of the Damask pattern of Damascus steels. Mater Charact, 2001, 47: 79

7. Verhoeven J D, Baker H H, Peterson D T, et al. Damascus Steel, Part III—The Wadsworth-Sherby mechanism. Mater Charact, 1990, 24:205

8. Verhoeven J D, Pendary A H, Gibson E D. Wootz Damascus steel blades. Mater Charact, 1996, 37: 9

9. Verhoeven J D, Pendary A H. Studies of Damascus steel blades: Part I—Experiments on reconstructed blades. Mater Charact, 1993, 30:175

10. Verhoeven J D, Pendary A H, Berge P M. Studies of Damascus steel blades: Part II—Destruction and reformation of the patterns. Mater Charact, 1993, 30: 187

11. Verhoeven J D, Pendray A. The mystery of the Damascus sword. Muse, 1998, 2: 35

Here’s a link to and a citation for the paper (you will likely need Chinese language skills to read it, although there is an English language abstract on the page),

Theoretic analysis on the mechanism of particular pattern formed on the ancient Damascus steel blades by LUO HaiWen, QIAN Wei, and DONG Han. Chinese Science Bulletin, 2014(9)

I believe the paper is behind a paywall. Finally, I hope the researchers are able to obtain a piece of genuine Damascus steel blade for their studies.