Investigation of the Effects of GP Zones Formation on the Properties of AA2090 Alloy

2008 ◽  
Vol 273-276 ◽  
pp. 18-21 ◽  
Author(s):  
Shahram Ahmadi ◽  
Ali Shokuhfar ◽  
Arash Rezaei
Keyword(s):  
Mechanical Properties ◽  
Electrical Resistance ◽  
Natural Aging ◽  
Physical And Mechanical Properties ◽  
Tensile Tests ◽  
Differential Scanning Calorimetric ◽  
Endothermic Effect ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys

To respond the need of industries to the new materials with higher specific modulus and lower density than those of the older Al alloys, aluminum- lithium alloys have been invented and improved. Aging process is one of the most important methods to improve the mechanical properties of aluminum- lithium alloys which are in the heat treatable category of aluminum alloys. Low temperature and natural aging processes cause the "short range diffusion" of Cu atoms in the aluminum and the formation of the GP zones. In this research, stability of GP zones and the effects of these areas on physical and mechanical properties of AA2090 alloy were investigated by hardness, electrical resistance, DSC (differential scanning calorimetric) and tensile tests. Results show that endothermic effect in the DSC diagrams of AA2090 alloy at 180°C to 240°C can be related to the enthalpy of GP zones dissolution. Formation of GP zones in the structure increases hardness, tensile strength and electrical resistance of Al- Li C u (2090) alloys.

Study of the heat treatment effect on the structure and mechanical properties welded joints of aluminum-lithium alloys V-1461 and V-1469

2019 ◽  
Vol 85 (7) ◽  
pp. 28-35
Author(s):  
Aleksey A. Skupov ◽  
Aleksey V. Scherbakov ◽  
Svetlana V. Sbitneva ◽  
Eva A. Lukina
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Rare Earth ◽  
Welded Joints ◽  
Artificial Aging ◽  
Welded Joint ◽  
Filler Materials ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys

The use of rare earth elements for alloying of aluminum alloys is a promising direction nowadays — filler materials doped with rare earth metals (REM) improve the mechanical properties of welded joints of high-strength aluminum-lithium alloys compared to serial filler material. The results of studying the effect of the composition of alloyed filler materials Sv1209 and Sv1221 and heat treatment mode on the mechanical properties and structure of welded joints of high-strength aluminum-lithium alloys B-1461 and B-1469 are presented. It is shown that the use of filler materials alloyed with rare earth metals in combination with full heat treatment (quenching and artificial aging) carried out after welding provide an increase in the strength characteristics of the welded joint to the level of strength of the base material with sufficiently high ductility and toughness. Metallographic study of welded joints after heat treatment revealed a fine-grained structure in the center of welds attributed to alloying of the filler with REM. Transmission electron microscopy is used to study precipitated hardening phases in welded joints. The round-shaped phase Al3(Sc, Zr) and a fine δ’-phase precipitated upon cooling of the welded joint are present in weld adjacent zone of V-1469 alloy. At the same time, artificial aging after welding results in formation of copper-containing Ω’- and θ’-phases. Quenching and artificial aging of the welded joint resulted in an increase in the size of precipitated hardening T1’-, S’-, θ’-phases and density of their distribution in the grain volume in the heat-affected zone of V-1461 alloy. Thus, heating upon welding leads to uneven phase precipitation, whereas additional artificial aging aggravates the non-uniformity of decomposition through partial dissolution of some phases and coarsening of the other.

The Effect of Precipitation Aging on the Mechanical Behavior and Microstructure of Aluminum-Lithium Alloys

2001 ◽  
Author(s):  
James M. Fragomeni
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Size Distribution ◽  
Quantitative Methods ◽  
Direct Consequence ◽  
Interparticle Spacing ◽  
Intermetallic Precipitates ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys

Abstract The effect of variations in microstructure as a consequence of heat treating and aging on the mechanical properties of aluminum-lithium alloys was studied. The thermal treatments and composition were correlated to the microstructure and subsequent mechanical behavior of aluminum-lithium and aluminum-lithium-copper alloys that were solution heat treated and artificially aged for a series of aging times and temperatures. The underaged, peak-aged, and overaged thermal heat treatments were considered in determining the effect of the microstructure and processing on the mechanical properties. Standard ASTM tensile testing of the alloys was performed to determine mechanical properties such as yield strength, ductility, and ultimate tensile strength. Quantitative microscopy of the intermetallic precipitates was performed to related the measured deformation behavior to the microstructural features. Thus, the intermetallic precipitates in the microstructure which impede dislocation motion and control the precipitation strengthening response as a function of aging practice were measured by quantitative methods, and are the basis for controlling the mechanical behavior depending on their size distribution, average size, and interparticle spacing. The microstructure was studied, and measurements were made to determine the size, distribution, and morphology for the intermetallic strengthening precipitates as a function of the processing and composition. For the aluminum-lithium alloys studied, the primary strengthening was a direct consequence of ordered coherent Al3Li intermetallic precipitates which were uniformly distributed throughout the microstructure, which restricted the glide motion of dislocations during plastic deformation.

Investigation of Homogenization Treatment in Al- Li- Cu- Zr Alloys

2008 ◽  
Vol 273-276 ◽  
pp. 536-541 ◽  
Author(s):  
Arash Rezaei ◽  
Shahram Ahmadi ◽  
Ali Shokuhfar ◽  
I. Foroutan
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloys ◽  
Grain Boundaries ◽  
Constant Temperature ◽  
Aerospace Structures ◽  
Homogenization Treatment ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-Lithium alloys were developed as major replacements for existing aluminum alloys to reduce the weight of aircraft and aerospace structures. Mechanical properties of Al-Li alloys greatly depend on solidification conditions. Other than reducing the microsegregation, homogenization treatment has other effects on the microstructure of Al-Li ingots. In this research, effects of homogenization treatment at constant temperature (500°C) on the precipitation in the microstructure of Al-1Li-3Cu-0.1Zr (wt %) and Al-2Li-3Cu- 0.1Zr (wt %) specimens have been investigated. Results show that homogenization at 500°C for 24 hours not only increases the hardness and phases precipitating in grain but also reduces microsegregation of Fe in grain boundaries.

Development of Aluminum-Lithium Alloys Processed by the Rheo Container Process

2006 ◽  
Vol 116-117 ◽  
pp. 513-517 ◽  
Author(s):  
Roger Sauermann ◽  
Bernd Friedrich ◽  
T. Grimmig ◽  
M. Buenck ◽  
Andreas Bührig-Polaczek
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Collaborative Research ◽  
Induction Melting ◽  
High Quality ◽  
Aluminum Lithium ◽  
Semi Solid ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys

This investigation describes the development and evaluation of thixoformable alloys on Al-Li-Mg basis in the scope of the collaborative research center SFB 289 at RWTH Aachen University. Scandium and zirconium was added to Al-Li2.1-Mg5.5 (A1420) with the aid of DoE (Design of Experiments) and precursor billets were manufactured by pressure induction melting (PIM). To evaluate the thixoformability of the synthesized alloys high-quality semi solid processed demonstrators were manufactured by the Rheo-Container-Process. Subsequent heat treatment raised the mechanical properties to maximum values of tensile strength of 432MPa, yield strength of 220MPa and an elongation of 13%. The RCP-Process was designed for the special requirements of this high reactive alloy. The paper will present extraordinary benefits in terms of properties and process simpleness for the semi-solid processing of Al-Li alloys.

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