Infrared Brazed Joints of Ti50Ni50 Shape Memory Alloy and Ti-15-3 Alloy Using Two Ag-Based Fillers.

Chieh Lin,Tsung-En Yang,Ren-Kae Shiue,Shyi-Kaan Wu

doi:10.3390/ma12101603

Abstract

The wettability, microstructures, and bonding strength of infrared brazing Ti-15-3 and Ti50Ni50 shape memory alloy using 72Ag-28Cu (wt.%) and 68.8Ag-26.7Cu-4.5Ti (wt.%) filler metals have been investigated. Only Ticusil® active braze readily wets both Ti50Ni50 and Ti-15-3 substrates. Wetting of eutectic 72Ag-28Cu melt on Ti50Ni50 base metal is greatly ameliorated by adding 4.5 wt.% Ti into the alloy. The brazed Ti-15-3/BAg-8/Ti50Ni50 joint consists of Cu-Ti intermetallics in the Ag-rich matrix. The formation of interfacial Cu(Ti,V) and (CuxNi1−x)2Ti intermetallics next to Ti-15-3 and Ti50Ni50 substrates, respectively, is attributed to the wetting of both substrates. The brazed Ti-15-3/Ticusil®/Ti50Ni50 joint shows a vigorous reaction, which results in the formation of a large amount of Ti2Ni intermetallics in the joint. The maximum joint strengths using BAg-8 and Ticusil® filler metals are 197 MPa and 230 MPa, respectively.

Highlights

Ti50 Ni50 shape memory alloy (SMA) possesses excellent pseudoelasticity and shape memory effect [1,2]
Ti-15-3/Ticusil® /Ti50 Ni50 joint shows a vigorous reaction, which results in the formation of a large amount of Ti2 Ni intermetallics in the joint
Ti50 Ni50 SMA was made by using a vacuum arc remelter with pure titanium and nickel pellets

Summary

Introduction

Ti50 Ni50 shape memory alloy (SMA) possesses excellent pseudoelasticity and shape memory effect [1,2]. Experimental results demonstrate that Ti50 Ni50 SMA is characterized by a very good biocompatibility [3,4,5]. It has led to extensive applications in biomedicine and engineering [6,7,8]. Titanium alloys have good specific strength as well as corrosion resistance, so they are widely applied in medical and aerospace applications. Ti-15-3 is a type of β-Ti alloy that has excellent forming characteristics at low temperatures [9]. Its chemical composition in wt.% is 3 Al, 3 Cr, 3 Sn, 15 V, and balance Ti. The strength of heat-treated Ti-15-3 primarily results from dispersed α-Ti precipitates in a β-Ti matrix [9]

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Results

Conclusion