Trace Amounts Of Scandium Research Articles

Microstructure and fatigue behavior of MIG-welded joints of 6005A aluminum alloy with trace amounts of scandium

Extruded plates of 6005A aluminum alloy with 0.07 wt% Sc (referred to as M6005A alloy) was metal-inert-gas-welded (MIG-welded) with ER5087 filler wire. The microstructure, mechanical properties, and fatigue behavior of the joints were studied. Compared with the base material (BM), recrystallization occurred and the formation of the coarse β' phase was evident in the heat-affected zone close to the weld zone (HAZ 2), which resulted in a significant decrease in the mechanical properties of HAZ 2. However, trace Sc inhibited the growth of the recrystallized grains in the HAZ 2, strengthening the α-AlFeSi and β'′ phases in the BM, which drastically improved the mechanical properties of the BM. In the weld zone (WZ), grains were significantly refined since the presence of Al3(Sc, Zr) particles promoted the nucleation of such grains in the WZ, and the particles also promoted the non-uniform nucleation of the α-AlFeSi phase, which significantly improved the mechanical and fatigue properties of the WZ. The hardness distribution of the MIG-welded joint shows a double-W shape. The lowest hardness is 55 HV, observed in the HAZ 2. The ultimate tensile strength (UTS) and conditional fatigue strength (107 cycles) of the MIG-welded joint of M6005A-T6 are 238.5 MPa and 108.2 MPa, respectively, 38 MPa and 13 MPa higher than the those of the MIG-welded joint of 6005A-T6 alloy, respectively.

Microstructure and Fatigue Behavior of Mig-Welded Joints of 6005a Aluminum Alloy with Trace Amounts of Scandium

Microstructure and Fatigue Behavior of Mig-Welded Joints of 6005a Aluminum Alloy with Trace Amounts of Scandium

Microstructure and mechanical properties of Al–Si–Mg–Cu–Ti alloy with trace amounts of scandium

ABSTRACTThe effect of Sc on the microstructure and mechanical properties of Al–Si–Mg–Cu–Ti alloy was investigated. Results obtained in this research indicate that, with increasing Sc content, the microstructure of the investigated alloys exhibits finer equiaxed dendrites with rounded edges and the morphology of the eutectic Si shows a complete transition from a coarse needle-like structure to a fine fibrous structure upon modification of eutectic Si. Subsequent T6 heat treatment had further induced the precipitation of nano-scaled secondary Al3(Sc, Ti) phase, as well as spheroidisation of eutectic Si. Combined with T6 heat treatment, the ultimate tensile strength, yield strength, percentage elongation and hardness were achieved in 0.20 wt-% Sc-modified alloy.

Determination of scandium in acid mine drainage by ICP-OES with flow injection on-line preconcentration using oxidized multiwalled carbon nanotubes

An on-line scandium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry associated with flow injection was studied. Trace amounts of scandium were preconcentrated by sorption on a minicolumn packed with oxidized multiwalled carbon nanotubes, at pH 1.5. The retained analyte was removed from the minicolumn with 30% (v/v) nitric acid. A total enrichment factor of 225-fold was obtained within a preconcentration time of 300s (for a 25mL sample volume). The overall time required for preconcentration and elution of 25mL of sample was about 6min; the throughput was about 10 samples per hour. The value of the detection limit was 4ngL−1 and the precision for 10 replicate determinations at 100ngL−1 Sc level was 5% relative standard deviation, calculated from the peak heights obtained. The calibration graph using the preconcentration system was linear with a correlation coefficient of 0.9996 at levels near the detection limits up to at least 10mgL−1. After optimization, the method was successfully applied to the determination of Sc in an acid drainage from an abandoned mine located in the province of San Luis, Argentina.

On-line preconcentration and vapor generation of scandium prior to ICP-OES detection

A novel on-line scandium preconcentration system implemented with chemical vapor generation associated to inductively coupled plasma optical emission spectrometry (VG-ICP-OES) was studied. The variables involving the preconcentration and the vapor generation were optimized using both full factorial and central composite designs, respectively. Trace amounts of scandium were preconcentrated by sorption on a minicolumn packed with activated carbon (AC) at pH 7.0. The analyte retained was removed from the minicolumn with 10% (v/v) hydrochloric acid. After that, volatile species of scandium were generated by merging the acidified sample and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the inductively coupled plasma torch. For the preconcentration/vapor generation procedure, an enhancement factor of 240-fold (10 for VG with respect to the traditional pneumatic nebulization and 24 for preconcentration) for a sample volume of 25 ml was obtained. The detection limit (DL) obtained was 4.0 μg l−1. The precision (RSD) for ten replicate determinations at a level of 100 μg l−1 was 4.0%. Potential interfering effects on the Sc signal were examined. The methodology was applied to the determination of scandium in river water samples.

Highly sensitive spectrofluorimetric determination of trace amounts of scandium with salicylaldehyde salicyloylhydrazone

The fluorescent reaction of salicylaldehyde salicyloylhydrazone (SASH) with scandium was studied in detail. Based on this chelation reaction, a highly sensitive spectrofluorimetric method was developed for the determination of scandium in ethanol–water (1 + 1 v/v) medium at pH 5.0. Under these conditions, the Sc–SASH complex had excitation and emission maxima at 388 and 465 nm, respectively. The linear range of this method was 0.40–100 ppb and the detection limit was 0.12 ppb of scandium when a standard additions method was used in the assay. The molar ratio of scandium to the reagent was found to be 1:1. The effect of interferences was studied. The proposed method was successfully used to determine trace amounts of scandium in geological soil samples. Extraction with 1-phenyl-3-methyl-4-benzoylpyrazolone– benzene from formic acid–sodium formate medium (pH 3) was used to separate Sc from interfering elements in the soil samples.

Fluorimetric Determination of Trace Amounts of Scandium with Di-2-pyridyl-ketone 2-Furoylhydrazone

Abstract The reaction of Di-2-pyridyl-ketone 2-furoylhydrazone (DPFH) with scandium in an aqueous ethanolic medium (4% v/v of ethanol) has been studied. A spectrofluorimetric method based on the formation of a fluorescent complex is proposed for the determination of scandium. With excitation at 387 nm, the scandium (III) chelate has an emission maximum at 492 nm; the reaction is carried out at pH 6.5–7.5. The accuracy and precision of the method are demonstrated by the analysis of synthetic mixtures containing various amounts of scandium. 10 – 140 ng/ml of scandium can be determined with a relative error of ±1.3%.