A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 1 2 5 example, a piece of wood as a guide in its interior. The average microhardness data for Cone 1 is 121 HV, Cone 2 is 109 HV, and Cone 3 is 144 HV. Observing the three cones macroscopically, their morphology is very similar (Fig. 2a). From the metallographic study (Fig. 2b), the images show structures consistent with α-brass and leaded brass (Cu-Zn-Pb). The metallographic structure is very similar to brass alloy (Cu-Zn) and lead appears as small dark particles at the grain boundaries. The images show equiaxed grains, polygonal grains, annealed twins, slip lines, and void segregation. The chemical composition values as shown in Fig. 2 are: for Cone 1: Cu is 71.1% and Zn is 24.4%; for Cone 2: Cu is 66.7% and Zn is 27.9%; for Cone 3: Cu is 66.6% and Zn is 26.2%. The chemi- cal analysis of the three cones corresponds to the current alloys for forged brass α, that is, brass type α with lead (Cu-Zn-Pb), precisely it is cartridge brass 70% C36000 for Cone 2 and Cone 3. In the case of Cone 1, the alloy is equivalent to that of cartridge brass 70% C26000[10]. CONCLUSIONS The work done to study these artifacts from the era before the arrival of the Spanish reiterates the role metallurgists played in their communities. They didn’t consider metalworking an Fig. 2 — (a) Brass cones from the post-1600s era, (b) their corresponding microstructures, and (c) chemical compositions. (a) (b) (c)
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