Abstract:This work aimed to investigate and critically analyze the differences in microstructural features and thermal stability of Cu-11.3Al-3.2Ni-3.0Mn-0.5Zr shape memory alloy processed by selective laser melting (SLM) and conventional powder metallurgy. PM specimens were produced by sintering 106-180 μm pre-alloyed powders under an argon atmosphere at 1060 °C without secondary operations. SLM specimens were consolidated through melting 32-106 μm pre-alloyed powders on a Cu-10Sn substrate. Mechanical properties were measured through Vickers hardness testing. Differential scanning calorimetry was conducted to assess the martensitic transformation temperatures. X-ray diffraction patterns were collected to identify the metallurgical phases. Optical and scanning electron microscopy was used to analyze the microstructural features. b ′₁ martensite was found, irrespective of the processing route, although coarser martensitic variants were present in PM-specimens. In conventional powder metallurgy samples, intergranular eutectoid constituents and stabilized austenite also formed at room temperature. PM-specimens showed similar average hardness values to the SLM-specimens, albeit with high standard deviation linked to the porosity. The specimens processed by SLM showed reversible martensitic transformation (T₀=171 °C). PM-processed specimens did not show shape memory effects.

Key words: shape memory alloys; powder metallurgy; additive manufacturing; selective laser melting; Cu-based alloys