The Effects of 600°C Annealing and Tensile Plastic Deformation on Mechanical Properties of Cu <sub>62</sub>zn <sub>38</sub> and (cu <sub>62</sub>zn <sub>38</sub>)97.5al <sub>2.5</sub> Shape Memory Alloys

The effects caused by annealing at 600℃ and tensile plastic deformation on microstructural features of Cu62Zn38 and (Cu62Zn38)97.5Al2.5 shape memory alloys (SMAs) have been investigated through analyses of X-ray diffraction (XRD), scanning electron microscopy (SEM) and secondary electron (SE). The tensile mechanical properties (including yield and tensile strength, tensile ductility, strain hardening rate) of two SMAs before and after annealing were carried out by using a universal tensile testing machine. After annealing as well as different degrees of tensile deformation, the hardness variation is studied in combination with phase transformation, dislocation accumulation and microstructure evolution. Through in-depth analysis on microstructure-dependent mechanical properties, it is found that faced centered cubic (FCC) α phase (Cu62Zn38) and (FCC) β phase (Cu62Zn38) have opposite properties under plastic deformation, i.e., the former has better capability to generate dislocation and is relatively poor in grain size refinement while the latter is opposite to the former. The body centered cubic (BCC) β' phase ((Cu62Zn38)97.5Al2.5) resembles (FCC) β phase (Cu62Zn38), has lower ability of dislocation accumulation and it is good in refining its grains under plastic deformation.The effects caused by annealing at 600℃ and tensile plastic deformation on microstructural features of Cu62Zn38 and (Cu62Zn38)97.5Al2.5 shape memory alloys (SMAs) have been investigated through analyses of X-ray diffraction (XRD), scanning electron microscopy (SEM) and secondary electron (SE). The tensile mechanical properties (including yield and tensile strength, tensile ductility, strain hardening rate) of two SMAs before and after annealing were carried out by using a universal tensile testing machine. After annealing as well as different degrees of tensile deformation, the hardness variation is studied in combination with phase transformation, dislocation accumulation and microstructure evolution. Through in-depth analysis on microstructure-dependent mechanical properties, it is found that faced centered cubic (FCC) α phase (Cu62Zn38) and (FCC) β phase (Cu62Zn38) have opposite properties under plastic deformation, i.e., the former has better capability to generate dislocation and is relatively poor in grain size refinement while the latter is opposite to the former. The body centered cubic (BCC) β' phase ((Cu62Zn38)97.5Al2.5) resembles (FCC) β phase (Cu62Zn38), has lower ability of dislocation accumulation and it is good in refining its grains under plastic deformation.