Alloying aluminum alloys with scandium and zirconium additives

Abstract

In recent years Russian specialists have developed industrial weldable aluminum alloys alloyed with a small amount of scandium. Scandium added to existing weldable aluminum alloys improves considerably the set of their operational properties. In addition, the presence of scandium makes it possible to create new materials superior to traditional aluminum alloys. The present paper is devoted to problems of simultaneous alloying of aluminum alloys with scandium and zirconium.New" alloys with scandium additives can be divided into four groups in accordance with the system on which the alloys are based, namely: (1) weldable alloys based on the AI -Mg system and not strengthened thermally; (2) thermally strengthened high-strength weldable alloys based on the AI-Zn-Mg system; (3) thermally strengthened weldable alloys of intermediate or high strength that are based on the AI -Li system; (4) thermally strengthened high-strength aircrat~ alloys based on the AI -Zn -Mg -Cu system.Weldable AI -Mg alloys not strengthened thermally and alloyed with scandium have higher strength parameters than the base metal and stronger welded joints than their industrial scandium-free counterparts (see Table I).A comparative analysis of the properties of alloys with the same content of magnesium showed that the addition of scandium increases considerably the parameters o b (by 80-120N/ram 2) and o02 (by 150-170N/ram 2) of annealed sheets and the parameter o b of welded joints (by 70 -150 N/ram2).High-strength thermally strengthened weldable alloys based on the AI-Zn-Mg system with an addition of scandium are also alloyed with a small amount of copper (0.3 -0.5%), which improves considerably the resistance of the base metal and especially that of welded joints to corrosion cracking and slow disruption. It should be noted that the presence of copper intensifies the formation of hot cracks in welding of aluminum alloys. This drawback is eliminated by the introduction of a combined scandium, zirconium, and titanium additive. Two alloys in the AI-Zn-Mg system with scandium and copper additives have been developed, namely, All-Russia Institute of Light Alloys. 01970 (AI -5.4% Zn -2.0% Mg -0.3% Mn -0.35% Cu -0.25% Sc -0.1% Zr) and 01975 (AI -5.4% Zn -2.0% Mg -0.3% Mn -0.25% Cu -0.08% Sc -0.1% Zr). Semiproducts from these alloys have a strength of the base metal a b = 500 N/mm 2 and of welded joints without heat treatment (3-month aging aff~r the welding) a~' = 450 N/ram 2. The safe level of stresses in welded joints of alloys 01970 and 01975, which characterizes the corrosion resistance under stress and the resistance to slow disruption, is rather high (a~ = 225 and 200 N/mm 2, respectively). In addition to the high strength and resistance to corrosion under stress, the alloys are characterized by a high crack resistance and a low anisotropy of the properties.Advanced weldable alloys with scandium additives have been developed in the AI-Li-Mg system, namely, 01421 (AI-5.5% Mg-9.0% Li-0.2% Sc-0.1% Zr), and in the A! -Li -Cu system, namely, 01460 (A...

Influence of Overaging on the Superplastic Behavior of an Al-Zn-Mg-Cu-Zr-Sc Alloy

“…These particles nucleate rapidly at high number densities, are homogeneously distributed, and coarsen quite slowly. 16,17) These Al 3 (Sc x Zr 1Àx ) particles stabilize the grain structure of the alloy and prevent recrystallization after hot working by pinning grain and subgrain boundaries. In our previous study, 13) we found that Al 3 (Sc x Zr 1Àx ) particles showed significant interaction with the dislocations and grain boundaries in a cold-rolled Al-6Mg-0.4Sc-0.13Zr alloy at temperatures of 400 C and 450 C. The Al-6Mg-0.4Sc-0.13Zr alloy resulted in poor ductility at 400 C and 450 C; it was not until the alloy was deformed at temperature above 500 C that the alloy exhibited excellent ductility of 1100%.…”

Developing Sc and Zr containing Al-B C metal matrix composites for high temperature applications /

“…Kinetics of the variation of microhardness of Al-0.2wt.% 31 Sc(O) and Al-0.2wt.%Sc-0.15 wt.%Zr (•) alloys in annealing at 400°C a and 450°C b (redrawn form Ref [111]). …”

“…Although the Al-Sc binary alloys displayed promising properties, especially at elevated temperatures, the utilization of these binary alloys was limited because of (1) the medium diffusivity of scandium in the aluminum and (2) the high cost of scandium [111,112]. On account of this, ternary alloys have been developed.…”

Recrystallization features of deformable aluminium-magnesium alloys with scandium

“…Более эффективным является дополни-тельное введение в эти сплавы циркония и скандия [2,3,[8][9][10][11][12][13].…”

“…Этот способ упрочнения обширно используется в промышленности для повы-шения прочности листов и реже плит, предел прочности при этом повышается примерно на 25 %, а предел текучести -в 2 раза по сравне-нию с отожженным состоянием. Основные недостатки этого способа упрочнения: пони-женная пластичность (6-9 %), снижение проч-ности материала в зоне сварки и невозмож-ность его использования для большинства остальных полуфабрикатов, кроме листов и плит [1][2][3][4][5][6][7].Более эффективным является дополни-тельное введение в эти сплавы циркония и скандия [2,3,[8][9][10][11][12][13].Скандий оказался наиболее эффектив-ным легирующим компонентом из всех ранее известных; выделения фазы Al 3 Sc значитель-но более дисперсны, чем выделения алюми-нидов Zr. Скандий при содержании в сплавах от 0,15 до 0,25 % обеспечивает весьма высо-кий эффект дисперсионного твердения слит-ков при правильно подобранных температур-ных режимах их обработки [3][4][5].…”