1 2 3 4 5 6 7 8 9 10

39.289 37.880 37.121 36.883 36.492 36.588 36.225 35.968 36.015 35.444

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Aspects Regarding Thermal-Mechanical Fatigue of Shape Memory Alloys http://dx.doi.org/10.5772/intechopen.77991 33

Figure 15. Optical microstructure, in forged state, HNO3 30% attack, (100).

Figure 16. SEM microstructure, in forged state, HNO3 30% attack, (5000).


Table 5. Thermal conductivity for sample in forged state.

• aluminum-copper AlCu3 by 20.5%

found and also in the case of forged sample.

9. Thermal conductivity analysis of samples in forged state (Table 5)

Figure 14. Chemical compounds distribution for Cu75Zn18Al6 alloy, in a forged state.

processing through plastic deformation and obtaining of parts.

8. Structural analysis of sample in forged state through optical and SEM microscopy (Figures 15

Figure 13. (a) Heating furnace and forged parts; (b) forging of cast; (c) hot forged sample (850–900C).

The same martensitic structure, mixed, with different shapes: parallel plates, arrow head, is

The hot plastic deformation has a lower influence on thermal conductivity; the measured values are falling in specific limits of SMA, based on cooper, found in different stages of

• copper-zinc Cu5Zn8 by 33.3%

• copper-zinc CuZn by 20.6%

• α-Cu0.61Zn0.39 by 25.6%

32 Shape-Memory Materials

and 16)

#### 10. Heat treatment of quenching to put in solution

The forged samples were processed through machining at standard dimensions according to the experimental tests. These samples are subjected to quenching heat treatment. The parameters of heat treatments are the following: (1) heating with furnace until 800C; (2) maintaining for temperature uniformization and finishing the structural transformation, for an hour; (3) rapid cooling in water at ambiance temperature (Figures 17 and 18).

The martensitic structure from quenched sample is present, having predominantly the shape

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The decrease of thermal conductivity for quenched sample more than six times over cast sample or forged sample, transform the SMA in a thermal barrier, following in the heating-

After the heat treatment, the samples were subjected to an elongation with 3% deformation grade (Figure 20). The controlled elongation was realized on a traction machine, Instron 3382

The dilatometric analysis records the length modifications for a sample, when it is exposed to a temperature variation. This modification of length can be reversible. Through dilatometric analysis can determine the transformation points in solid states, specific to the analyzed alloy. The determination of these transformation points is important for the applications in which are

The dilatometric analysis of Cu75Zn18Al6 alloy was made on a differential dilatometer, Linseis L75H/1400 model [3]. In the heating time, with a constant heating rate (5C/min), the alloy
