Al-4 wt.% Cu alloy

Shock-recovery experiments by Gray [10] were conducted to assess directly if the strain-path reversal inherent to the shock contains a traditional microstructurally controlled Bauschinger effect for a shock-loaded two-phase material. Two samples of a polycrystalline Al-4 wt.% Cu alloy were shock loaded to 5.0 GPa and soft recovered in the same shock assembly to assure identical shock-loading conditions. The samples had two microstructural... 

Fig. 10.4. Room temperature microstructures in the Al + 4 wt% Cu alloy, (a) Produced by slow cooling from 550°C. (b) Produced by moderately fast cooling from 550°C. The precipitates in (a) are large and far apart. The precipitates in (b) are small and close together.

To age harden our Al-4 wt% Cu alloy we use the following schedule of heat treatments. 

Fig. 10.10. Detailed TTT diagram for the Al-4 wt% Cu alloy. We get peak strength by ageing to give 8". The lower the ageing temperature, the longer the ageing time. Note that GP zones do not form above 1 80°C if we age above this temperature we will foil to get the peak value of yield strength.

The Al-4 wt% Cu alloy of the example can exist at 20°C in three different states. Only one - the slowly cooled one - is its equilibrium state, though given enough time the others would ultimately reach the same state. At a given temperature, then, there is an equilibrium constitution for an alloy, to which it tends. 

Fig. 5.9 Ne field ion images of a GP[1] zone emerging from a (024) plane of an Al-4 wt% Cu alloy. This alloy was grown by Bridgeman method. After a homogenizing treatment at 793 K for 1.7 x lOf5 s, single crystal samples with a longer axis parallel to [001] were prepared. They were quenched into ice water and then aged at 403 K for 6 x 104 s under the tensile stress of 73.5 MPa along the [001]. Between a and b, 11 (024) layers were field evaporated, and between b and c, 16 more layers were evaporated. The distance between two Cu atoms should be 9.06 A as is shown in d. (Courtesy of M. Wada.)...

GP[2] zones, or two Cu 001 layers separated by a few aluminum layers, have also been observed in the field ion microscope in an aged Al-4 wt% Cu alloy.71 A GP[2] zone formed on the (200) plane and observed on the (022) surface of the [001] oriented tip can be observed as two rows of bright image spots if an odd number of the (200) atomic layers are present between the Cu layers. The imaging condition at the (022) surface is more complicated if an even number of the (022) layers are present... 

Carpenter et al. (1999) prepared, by sputter depositing on NaCl, a lOOnm Al film alloyed with 4 wt% Cu. This they stabilized for 1 h at 475°C, then aged for 4h at... 

To promote the activity and selectivity of Raney nickel catalysts, alloying of the starting Ni-Al alloy with metal was often used. For instance, Montgomery (ref. 4) prepared catalysts by activating ternary alloy powders of Al (58 wt %)-Ni (37-42 wt %) - M (0.5 wt %) where M = Co, Cr, Cu, Fe and Mo. All promoted catalysts tested were more active than the reference catalyst, in hydrogenation of butyronitrile. Molybdenum was the most effective promoter. With Cr or Ti, hydrogenation of isophtalonitrile on Raney nickel occurred at lower optimum temperature than with non activated nickel (ref. 5). It was shown that addition of Ti or Co to Raney nickel suppressed the formation of secondary amine (ref. 6). 

Pellets of CUAI2 alloy (53 wt. % Cu, 47 wt. % Al) and Cu-Al-Zn alloy (43.2 wt. % Cu, 39 wt. % Al, 17.8wt. % Zn), (3.8 mm x 5.4 mm dia), were leached in large excesses of two different leach solutions, 6.1 M sodium hydroxide and 0.62 M zincate in 6.1 M sodium hydroxide. Leaching was terminated by washing the pellets in distilled water to a pH of 7. The catalyst preparation procedure is described in greater detail elsewhere [7]. To simplify references to the four Raney catalysts Table 1 identifies them according to the precursor alloys and leach conditions used. 

Figure 4. Tensile flow curves of two Al-4.5 wt.% Cu reinforced with aluminium matrix composites, reinforced with angular and polygonal alumina particles of roughly the same size. The data show the significant improvements brought by matrix alloying (see Fig. 3) as well as the strong influence of the ceramic particle type on the composite mechanical performance. With the stronger ceramic, the material features high strength and acceptable tensile ductility despite the fact that it is more than 50% ceramic.

---