Phase Formation, Thermal Stability and Mechanical Properties of a Cu-Al-Ni-Mn Shape Memory Alloy Prepared by Selective Laser Melting

Selective laser melting (SLM) is an additive manufacturing process used to produce parts with complex geometries layer by layer. This rapid solidification method allows fabricating samples in a non-equilibrium state and with refined microstructure. In this work, this method is used to fabricate 3 mm diameter rods of a Cu-based shape memory alloy. The phase formation, thermal stability and mechanical properties were investigated and correlated. Samples with a relative density higher than 92% and without cracks were obtained. A single monoclinic martensitic phase was formed with average grain size ranging between 28 to 36 μm. The samples exhibit a reverse martensitic transformation temperature around 106 ± 2 °C and a large plasticity in compression (around 15±1%) with a typical “double-yielding” behaviour

Microstructure evolution and mechanical properties of Al-Zn-Mg-Cu alloy reprocessed by spray-forming and heat treated at peak aged condition

Machining chips of the alloy AA7050 were reprocessed by spray forming followed by hot-extrusion and heat treatment. The spray-formed deposit presented a microstructure with hardening η' precipitates within the matrix and equilibrium η precipitates at the grain boundaries, refined grains and low segregation of the main elements Zn, Cu and Mg. The final microstructure at peak aged condition is mainly composed by Guinier-Preston (GP) zones, η' metastable, η equilibrium , Al3Zr dispersoids and the coarse Al7Cu2Fe intermetallic. A well-defined precipitation free zone along grain boundaries was not observed. Good mechanical properties were achieved. © 2013 Elsevier B.V. All rights reserved

Phase transformation and shape memory effect of a Cu-Al-Ni-Mn-Nb high temperature shape memory alloy

The microstructure, phase transformation and shape memory effect of the high temperature shape memory alloy Cu-11.4Al-3.2Ni-3Mn-0.5 Nb (wt%) were investigated for the first time. The shape recovery ratio can achieve 73% when submitted to 690 MPa and the compressive stress of fracture of the alloy is 1560 MPa.</p