Shape memory alloys (SMA) are attracting considerable attention owing to possible applications from biomedical to aerospace. In particular, CuAlNi alloys present significant advantages associated with low cost, easy processing and superior thermo-electric conductivity over other SMAs such as the NiTi alloys. Characterization of some properties and structural changes caused by martensitic transformation are still open to investigation. The present work evaluated these characteristics in an as-cast plasma processed shape memory Cu-14wt.%Al4wt.%Ni, which was compression tested until fracture. Experimental results showed that an as-cast ingot presents not only chemical and phase homogeneity, but also microstructures composed of grains with martensitic morphology. Martensites β'₁ and γ'₁, as well as intermediary martensitic R and high temperature β₁ were identified by X-ray diffraction tests. It was found that the compressive deformation does not interfere in the phase composition and martensite morphology. However, compression changes the volumetric fractions and crystallographic orientation of the martensites. The mechanical behavior is characterized by an apparent elastic response until the fracture. The fractured surface exhibits brittle aspect like "river patterns" and evidence of intergranular rupture.

Elastic properties of materials and their changes with temperature are important for their applications in engineering. In the present study the influence of phase composition and temperature of AISI 4130 alloy on Young’s modulus (E_d), shear modulus (G_d), and damping (Q⁻¹) was carried out by the impulse excitation technique (IET). The material characterization was performed using confocal microscopy, XRD, SEM, HV, and dilatometry. A stable structure, composed of ferrite (BCC) and pearlite (α-Fe + Fe₃C), was obtained by annealing. Metastable structure of martensite (BCT) was obtained by quenching. The E_d, G_d, and Q⁻¹ were measured by varying the temperature from RT to 900 °C. The values of E_d and G_d, at RT, were determined as 201.5 and 79.2 GPa (annealed) and 190.13 and 76.5 GPa (quenched), respectively. In the annealed steel, the values E_d and G_d decrease linearly on heating up to 650 °C, with thermal expansion. In the quenched steel, weak changes occurred in the dilatometric curve, E_d, G_d, and Q⁻¹, in the range of 350–450 °C, which indicated decompositions of the martensitic phase. A sharp decrease in the moduli and high peak of Q⁻¹ were observed for both samples around 650–900 °C, revealing low lattice elastic stability of the phases during transformations α(BCC) + Fe₃Cγ(FCC).