Bronze Sword

Among the bronze weapons unearthed from the Terracotta Warriors Pit 1 and 2, the most fascinating ones are the sharp and tough Qin bronze long swords. The willow-shaped sword is thin, long and pointed, with a length of 81-94.8 cm. Qin-style bronze swords are not only long but also very sharp. Some of the swords were unearthed without rust, as clean as new, with sharp edges. The surface of these swords is grayish yellow, with fine organization and no trachoma. Moreover, the surface of the swords was finely filed and polished, extremely flat and shiny.

In 1994, another batch of bronze swords was found in Terracotta Warriors Pit 2. The length was 86 cm, and there were 8 prongs on the sword, which were extremely symmetrical and balanced. Archaeologists measured the eight prongs and found that they were less than a hair’s breadth in error. This is true of all 19 bronze swords that have been unearthed. These bronze swords have a dense structure, a shiny and smooth body, and a fine grain on the edge, with no interlacing of textures. They have been sleeping for more than 2,200 years and were still as bright and sharp as new when they were unearthed.

So why have these bronze swords remained unembroidered through the millennia? Electron microprobe and proton X-ray fluorescence analysis revealed a layer of chromium salt compound 10 to 15 microns thick on the surface of these bronze swords. This discovery immediately shocked the world, because this “chromium salt oxidation” treatment is an advanced process that only appeared in recent times, invented and patented in Germany in 1937 and in the United States in 1950. How did the Qin Dynasty people master chromium salt oxidation technology 2200 years ago?

While cleaning the over-hole of Terracotta Warriors Pit 1, archaeologists discovered that a bronze sword had been bent by a 150 kg terracotta figurine, which was bent more than 45 degrees. When the terracotta figurines were removed, an amazing miracle occurred. The narrow and thin bronze sword rebounded from the bend of more than 45 degrees to a straight state in an instant, naturally recovering its straight state. This exquisite skill of sword casting was astonishing, and the “morphological memory alloy” dreamed by contemporary metallurgists appeared in an ancient tomb more than 2000 years ago.