Minor Elements Cr Research Articles

Compositions of early Islamic glass along the Iranian Silk Road

The composition of archaeological glass reflects the geochemical nature of its raw materials. To determine the origins and distribution of early Islamic glasses from Iran, a set of 169 glass samples from five different sites was analysed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of 58 elements. The glasses were classified into six different plant ash glass groups, three of which were attributed to a Mesopotamian origin, while three further groups are presumed to represent regional Iranian productions. The ratios of MgO/CaO and K2O/P2O5 of the different groups reflect variations in the plant ash component. Minor elements Cr, Ti, Zr, La and Th and their ratios proved effective in distinguishing the base glass types. Mapping their frequency across the Iranian plateau revealed the relative movement of glass and likely source areas. The decline in the frequency of glass types with elevated Cr/La ratios east of the Zagros Mountain range confirms that elevated Cr/La ratios together with an augmentation of the magnesium levels are features of Mesopotamian glass production apparently inherited from the geochemical environment of the Euphrates and Tigris river valleys. Some exceptionally clean Mesopotamian glasses made from a quartz-rich silica with low levels of accessory minerals are consistent with ninth-century glass from Samarra, which was evidently traded widely along the Silk Road network. No evidence of local glass production was detected in Nishapur. The Iranian groups were produced from a quartz-rich silica source, high in thorium but with different zirconium contents resulting in different Th/Zr ratios. Aluminium concentrations tend to increase from west to east, with the highest values found among glass assemblages from Central Asia.

Effect of Minor Cr, Mn, Zr, Ti and B on Grain Refinement of As-Cast Al-Zn-Mg-Cu Alloys

Abstract The effects of joint addition of minor elements Cr, Mn, Zr, Ti and B on grain refinement of Al-Zn-Mg-Cu alloys were investigated by optical microscopy and scanning electron microscopy(SEM)as well as EDS. Results show that grains can be refined from 256 μm to 102 μm via adding (mass fraction) 0.04%Ti, 0.18%Zr and 0.008%B to the cast alloy. Joint addition of 0.20%Cr, 0.20%Mn, 0.04%Ti and 0.008%B may attain better grain refinement, and the average grain size is as fine as 55 μm. It is because atom clusters containing minor Cr and Mn help Al3Ti nucleation to become crystallization substrate. Joint adding of 0.20%Cr, 0.20%Mn, 0.03%Ti, 0.14%Zr and 0.006%B can result in a remarkable refinement with average grain size about 22 μm. This is because a part of Zr atoms enters the crystal nuclei of Al3Ti based on the atom clusters containing minor elements Cr and Mn to replace the Ti to form new crystal nuclei Al3(Tix, Zr1-x). While minor elements Cr and Mn decrease the surface tension between liquid aluminum and solid Al3Ti, Al3Zr and Al3(Tix, Zr1-x) particles, and impede the nucleation of particles to grow up.

The chemical composition of the silicate inclusions in the weekeroo station iron meteorite

A chemical analysis of the silicate portion of the iron meteorite, Weekeroo Station, is compared with those of other meteorite types. The composition is not similar to that of any chondrite type, however, it is similar to the residue of a bulk chondritic composition from which 50% olivine ( 85Fo) has been subtracted, with only the minor elements Cr and P showing significant anomalies. Within some silicate nodules there is textural evidence for silicate liquid immiscibility.