Laser surface remelting of a Cu-Al-Ni-Mn shape memory alloy

Author(s)

da Silva, Murillo Romero ^[1] ; Gargarella, Piter ^[2] ; Gustmann, Tobias ^[3] ; Botta Filho, Walter Jose ^[2] ; Kiminami, Claudio S. ^[2] ; Eckert, Juergen ^{[4, 5]} ; Pauly, Simon ^[3] ; Bolfarini, Claudemiro ^[2]

Affiliation

^[1] Univ Fed Sao Carlos, Postgrad Program Mat Sci & Engn, Rodovia Washington Luis, Km 235, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos, Dept Mat Engn, Rodovia Washington Luis, Km 235, BR-13565905 Sao Carlos, SP - Brazil

^[3] IFW Dresden, Inst Complex Mat, Helmholtzstr 20, D-01069 Dresden - Germany

^[4] Austrian Acad Sci, Erich Schmid Inst Mat Sci, Jahnstr 12, A-8700 Leoben - Austria

^[5] Univ Leoben, Dept Mat Phys, Jahnstr 12, A-8700 Leoben - Austria

• Document type: Journal article
• Source: MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING; v. 661, p. 61-67, APR 20 2016.
• Web of Science Citations: 16

Abstract

Cu-based shape memory alloys (SMAs) show better thermal and electrical conductivity, lower cost and are easier to process than traditional Ti-based SMAs, but they exhibit a lower ductility and lower fatigue life. These properties can be improved by decreasing the grain size and reducing microstructural segregations, which may be obtained using laser surface remelting treatments. The aim of the present work was to produce and characterize laser remelted Cu-11.85Al-3.2Ni-3Mn SMA plates. Twelve plates with the dimensions of 50 x 10 x 1.5 mm were produced by suction casting in a first step. The surface of the plates was remelted afterwards with a laser beam power of 300 W, hatching of 50% and using three different scanning speeds: 100, 300 and 500 mm/s. The plates were characterized by optical and scanning electron microscopy, X-ray diffraction, differential scanning calorimetry as well as by tensile and microhardness tests. The remelted region showed a T morphology, with average thickness of 52, 29 and 23 gm for the plates remelted with scanning speeds of 100, 300 and 500 mm/s, respectively. In the plates remelted with 100 and 300 mm/s, some pores were found around the center of the track, due to the keyhole instability. The same phase formed in the as-cast sample was obtained in the laser remelted coatings: the monoclinic beta'(1) martensitic phase with zig-zag morphology. However, the laser treated samples exhibit lower transformation temperatures than the as-cast sample, due to grain refinement at the surface. They also show an improvement in the mechanical properties, with an increase of up to 162 MPa in fracture stress, up to 2.2% in ductility and up to 20.9 HV in microhardness when compared with the as-cast sample, which makes the laser surface remelting a promising method for improving the mechanical properties of Cu-based SMAs. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 15/04134-7 - Laser surface remelting of the Cu-11.85Al-3.2Ni-3Mn (% WT) shape memory alloy
• Grantee: Murillo Romero da Silva
• Support Opportunities: Scholarships in Brazil - Master