<p>Structural, chemical, and thermal properties of Ni-lean, equiatomic, and Ni-rich high-temperature NiZrTiCu shape memory alloys with high concentrations of Zr (30 at.%) and Cu (15 at.%) were systematically investigated. Thermo-Calc CALPHAD software was used to assess thermodynamic stability and phase evolution, producing phase fields consistent with the ASM phase diagram for the binary NiTi alloy system. Experimentally, the Ni-lean, equiatomic, and Ni-rich alloys were vacuum arc melted to investigate the effects of annealing and aging on the material’s transformation temperatures, thermal hysteresis, and microstructure, revealing A_f temperatures considerably above the high-temperature threshold of ~ 115℃. For both annealed and aged samples, scanning electron microscopy with energy dispersive spectroscopy and synchrotron radiation X-ray diffraction microstructural analysis revealed the presence of (Ti,Zr)₂Ni precipitates, second-phase (Cu,Ni)₂Zr, and (Ti,Zr)₄Ni₂O_x oxides. The processability of the alloy by hot rolling at 700℃ showed a thickness reduction that was limited to ~ 5%. Overall, the results show that these NiTi-based SMAs with high concentrations of Zr and Cu exhibit transformation temperatures desirable for high-temperature actuation but suffer from poor processability, highlighting critical trade-offs for future alloy design.</p>