Dissimilar welding of NiTi and stainless steel(SS)for multifunctional device fabrication is challenging due to the brittle nature of intermetallic compounds(IMCs)that are formed in the weld zone.In this work,Ni and Nb...Dissimilar welding of NiTi and stainless steel(SS)for multifunctional device fabrication is challenging due to the brittle nature of intermetallic compounds(IMCs)that are formed in the weld zone.In this work,Ni and Nb interlayers were applied for the resistance spot welding(RSW)of NiTi and SS to replace the harmful Fe_(2)Ti phase and to restrict the mixing of dissimilar molten metals,respectively.Microstructural evolution and mechanical properties of the joints were investigated.It was shown that a conventional weld nugget was created in the absence of any interlayer in the welded joint suffering from traversed cracks due to the formation of brittle IMCs network in the fusion zone(FZ).By the addition of Ni from the interlayer,Fe_(2)Ti dominated weld nugget was efficaciously replaced by Ni_(3)Ti phase;however,the presence of the large pore and cracks reduced the effective joining area.The use of a Nb interlayer resulted in a fundamentally different joint,in which FZs at NiTi and SS sides separated by the unmolten Nb would suppress the mixing of dissimilar molten metals.Nb-containing eutectic structures with low brittleness formed at the interfaces,contributing to the enhancement of joint strength(increased by 38%on fracture load and 460%on energy absorption).A high-melting-point interlayer showed great potential to realize a reliable and high-performing RSWed NiTi-SS joint.展开更多
基金Natural Sciences and Engineering Research Council of Canada(NSERC)Canada Research Chairs(CRC)+1 种基金K.Z.acknowledges support from China Scholarship Council(CSC)J.P.O.acknowledges funding by national funds from FCT-Fundação para a Ciência e a Tecnologia,I.P.,in the scope of the projects LA/P/0037/2020,UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures,Nanomodelling and Nanofabrication–i3N.
文摘Dissimilar welding of NiTi and stainless steel(SS)for multifunctional device fabrication is challenging due to the brittle nature of intermetallic compounds(IMCs)that are formed in the weld zone.In this work,Ni and Nb interlayers were applied for the resistance spot welding(RSW)of NiTi and SS to replace the harmful Fe_(2)Ti phase and to restrict the mixing of dissimilar molten metals,respectively.Microstructural evolution and mechanical properties of the joints were investigated.It was shown that a conventional weld nugget was created in the absence of any interlayer in the welded joint suffering from traversed cracks due to the formation of brittle IMCs network in the fusion zone(FZ).By the addition of Ni from the interlayer,Fe_(2)Ti dominated weld nugget was efficaciously replaced by Ni_(3)Ti phase;however,the presence of the large pore and cracks reduced the effective joining area.The use of a Nb interlayer resulted in a fundamentally different joint,in which FZs at NiTi and SS sides separated by the unmolten Nb would suppress the mixing of dissimilar molten metals.Nb-containing eutectic structures with low brittleness formed at the interfaces,contributing to the enhancement of joint strength(increased by 38%on fracture load and 460%on energy absorption).A high-melting-point interlayer showed great potential to realize a reliable and high-performing RSWed NiTi-SS joint.
