Metallurgy development: Discovery and utilization of aluminum through history

Since the early human civilizations, the discovery and use of new materials and the development of new technologies have changed culture and influenced the development of the modern human environment. At the same time, innovations based on scientific discoveries and technological advances are connected to increasingly complex social and political structures and international relations, which have an impact on economic growth and social benefits. Unfortunately, the human capacity for technological and strategic innovation has most often been demonstrated under stressful conditions inspiring the phrase “necessity is the mother of invention”. The goal of this review is to examine the necessity that compelled mankind to search for metals, primarily focusing on the discovery of aluminum and the challenges represented by the complex nature of its minerals. Although men’s first contact with metal initiated with native copper and meteoritic iron, bronz was the first metallic material significantly impacting human society. The experiments with its chemical composition led to the development of metallurgical processes such as smelting, refining, and casting as well as mechanisms of economics and communication. The accidental discovery of iron in the process of copper ore refining gave mankind greater control over its environment, resulting in increased population and expanded settlements. Aluminum, as a brilliant white metal, was introduced to the world through the works of Wöhler and Deville. However, it became commercially available after electrolysis was discovered by Charles Martin Hall on February 23rd 1886 in a woodshed using home-made battery. A few months later, the similar results were obtained by Paul Louis Toussaint Héroult, so the process for electrolytic production of aluminum bears both of their names. As a symbol of modernity aluminum is used today in the automotive, aerospace, railway, marine, electric, and architectural applications. At the end of this work, it is superfluous to ask whether humanity would have been able to explore the universe and reach the stars if it had been restricted by stone, bones and wood

Procjena broja nodula i nodularnosti u odljevcima od nodularnog lijeva korištenjem toplinske analize

The effect of parameters which are identified and measured by thermal analysis on the nodule count and nodularity in ductile iron castings was analyzed in this paper. The obtained results show that the nodule count and nodularity increases with increasing the temperature of eutectic undercooling (TEP) and graphite factor 1 (GRF 1) and decreasing recalescence (TR), graphite factor 2 (GRF2) and value of the first derivative of the cooling curve at TS (d/dt TS). The processing of obtained results was performed by multiple regression analysis. Based on the measured thermal parameters, models for estimation of the nodule count and nodularity were established. The high correlation coefficients between the measured and the estimated values of the nodule count (nodularity) confirm that there is a tight correlation between the thermal parameters of ductile iron melt and microstructural features of ductile iron castings.U ovom radu je analiziran utjecaj parametara koji su registrirani i mjereni toplinskom analizom na broj nodula/mm2 i nodularnost u odljevcima od nodularnog lijeva. Dobiveni rezultati pokazuju da broj nodula/mm2 i nodularnost rastu s povećanjem temperature eutektičnog pothlađenja (TEP) i grafitnog faktora 1 (GRF 1), te smanjenjem rekalescencije (TR), grafitnog faktora 2 (GRF 2) i vrijednost prve derivacije krivulje hlađenja na solidus temperaturi (d/dt TS). Obrada dobivenih rezultata je provedena višestrukom regresijskom analizom. Na osnovi mjerenih toplinskih parametara, formirani su modeli za procjenu broja nodula/mm2 i nodularnosti. Visoke vrijednosti koeficijenata korelacije između mjerenih i procijenjenih vrijednosti broja nodula/mmm2 (nodularnosti) potvrđuju da postoji čvrsta korelacija između toplinskih parametara taline nodularnog lijeva i mikrostrukturnih značajki odljevaka od nodularnog lijeva

The effect of sodium and strontium on modification of eutectic silicon

Modification of eutectic (αAl+βSi) is usually performed during treatment of Al-Si based alloys in order to obtain higher mechanical properties. Chemical modification is usually performed using modifying elements such as Na and Sr. The research was performed in order to estimate the efficiency of Na and Sr additions in eutectic AlSi12 alloy using chemical analysis, simple thermal analysis (STA) and metallographic analysis. The metallographic analysis revealed fully modified (αAl+βSi) eutectic microstructure in alloy treated with Na. The Sr additions widened solidification interval and, lowered the eutectic area temperatures as indicated by STA

Influence of solution hardening on microstructure and mechanical properties of Al-2.5Mg-0.7Li alloy

Although utilization of lightweight aluminum alloys in transportation industry reduced harmful emissions and improves fuel economy, their further application is limited by low stiffness, low Young modulus and sensitivity to elevated temperatures. It was found that specific strength properties of aluminum alloys can be improved by Li additions. The beneficial effect is achieved by precipitation of hardening Al3Li precipitate. The microstructural and mechanical properties of Al-2.5 Mg-0.7 Li alloy were investigated in as cast and solution hardened condition. The microstructure constituents and thermo-mechanical properties for both conditions were determined and compared

Analysis of the low energy layering fracture in Al- 2.5Mg-0.7Li alloy

The mechanism of nucleation and propagation of low energy layering fracture, observed during thermo-mechanical testing of Al-2.5Mg-0.7Li alloy in as cast condition, was analyzed. Since the low energy layering fracture is affected by Li segregations and microstructural constituents’ development, solidification sequence of Al-2.5Mg- 0.7Li alloy was investigated in equilibrium and non-equilibrium conditions. Results of the investigations have shown that Mg has more pronounced effect on low energy layering fracture due to reducing solubility of Li in liquid phase and αAl, maximizing precipitation of hardening (Al3Li) δ’ phase, ternary (Al2LiMg) T phase and (Al8Mg5) β phase, and reducing ductility by solid solution hardening

Statistical Analysis of the Combined ECAP and Heat Treatment for Recycling Aluminum Chips Without Remelting

The main aim of this paper is to present an environmentally friendly method for aluminum recycling. Development of new recycling technologies in order to increase scrap reuse potential and CO2 emission savings are of the main importance for aluminum circular economy. In this paper, aluminum chips waste was recycled without any remelting phase in order to increase energy and material savings. The presented process is usually called solid state recycling or direct recycling. Solid state recycling process consists of chips cleaning, cold pre-compaction and hot direct extrusion followed by a combination of equal channel angular pressing (ECAP) and heat treatment. Influence of holding time during solid solution treatment and both artificial aging time and temperature on mechanical properties of the recycled EN AW 6082 aluminum chips were investigated. A comprehensive number of the experiments were performed utilizing design of experiments approach and response surface methodology. Regression models were developed for describe the influence of heat treatment parameters for presented solid state recycling process on mechanical properties of the recycled samples. Utilizing novel procedure high quality recycled samples were obtained with mechanical properties comparable with commercially produced EN AW 6082 aluminum alloy in T6 temper condition. Metallographic analysis of the recycled samples was also performed

The effect of sodium and strontium on modification of eutectic silicon

Modification of eutectic (αAl+βSi) is usually performed during treatment of Al-Si based alloys in order to obtain higher mechanical properties. Chemical modification is usually performed using modifying elements such as Na and Sr. The research was performed in order to estimate the efficiency of Na and Sr additions in eutectic AlSi12 alloy using chemical analysis, simple thermal analysis (STA) and metallographic analysis. The metallographic analysis revealed fully modified (αAl+βSi) eutectic microstructure in alloy treated with Na. The Sr additions widened solidification interval and, lowered the eutectic area temperatures as indicated by STA

Investigation of iron containing intermetallics in AlSi12 alloy with w (Mn/Fe) = 0.99

The precipitation of iron-rich intermetallic phases in AlSi12 alloy with manganese/iron weight ratio w (Mn/Fe) = 0.99 was investigated. Calculation of solidification sequence under equilibrium conditions, obtained using Computer Aided Thermodynamic Diagram Calculation, comprehended precipitation of α-Al15(FeMn)3Si2 and β-Al5FeSi. However, the microstructural investigations performed using light and electron microscopy indicated the lack of β- Al5FeSi in needle-like morphology. The intermetallic phases in Chinese script, transitional and polyhedral morphology were found, respectively. The results of Energy Dispersive Spectroscopy showed the minimum difference in the chemical composition between the intermetallic phases in Chinese script and polyhedral morphology due to high w (Mn/Fe) weight ratio

Investigation of iron containing intermetallics in AlSi12 alloy with w (Mn/Fe) = 0.99

The precipitation of iron-rich intermetallic phases in AlSi12 alloy with manganese/iron weight ratio w (Mn/Fe) = 0.99 was investigated. Calculation of solidification sequence under equilibrium conditions, obtained using Computer Aided Thermodynamic Diagram Calculation, comprehended precipitation of α-Al15(FeMn)3Si2 and β-Al5FeSi. However, the microstructural investigations performed using light and electron microscopy indicated the lack of β- Al5FeSi in needle-like morphology. The intermetallic phases in Chinese script, transitional and polyhedral morphology were found, respectively. The results of Energy Dispersive Spectroscopy showed the minimum difference in the chemical composition between the intermetallic phases in Chinese script and polyhedral morphology due to high w (Mn/Fe) weight ratio