This research investigates the diffusion bonding of hybrid aluminum (Al)–titanium (Ti) joints using a copper (Cu) interlayer in a vacuum environment. At 610 °C and 1 MPa pressure, partial melting of Al caused deformation and misalignment, while 520 °C showed no melting of Al–Cu at the interface. A rod-shaped precipitate with primarily Al was observed at 550 °C, and grain coarsening occurred at 580 °C at the interface, accompanied by increased Cu diffusion within the Al matrix for a bonding time of 45 min. A Ti–Al-based intermetallic layer formed on the Ti side, but voids and cracks were present in the Al–Cu diffusion region at 580 °C. Hardness variation resulted from microstructural changes due to bonding temperature, particularly near the bond line due to hard intermetallic compounds. Shear strength averaged 41 MPa at 550 °C and decreased to 33 MPa at 580 °C due to grain growth, voids, and crack propagation, causing brittle joint failure at the interface. X-ray diffraction on the fracture surfaces revealed that the failure of diffusion-bonded joints is attributed to fractures through the Ti–Al-based intermetallic compounds at the interface and unbonded region.
BoyerRR. An overview on the use of titanium in the aerospace industry. Mater Sci Eng A1996; 213: 103–114.
2.
VigneshRVPadmanabanR. Artificial neural network model for predicting the tensile strength of friction stir welded aluminium alloy AA1100. Mater Today Proc2018; 5: 16716–16723.
3.
HeinzAHaszlerAKeidelC, et al.Recent development in aluminium alloys for aerospace applications. Mater Sci Eng A2000; 280: 102–107.
4.
CookeKOAtiehAM. Current trends in dissimilar diffusion bonding of titanium alloys to stainless steels, aluminium, and magnesium. J Manuf Mater Process2020; 4: 39.
5.
GadakhVSBadhekaVJMulayAS. Solid-state joining of aluminum to titanium: a review. Proc IMechE Part L: J Materials: Design and Applications2021; 235: 1757–1799.
6.
ChenYChenSLiL. Influence of interfacial reaction layer morphologies on crack initiation and propagation in Ti/Al joint by laser welding–brazing. Mater Des2010; 31: 227–233.
7.
HuangJLiuYLiuS, et al.Process of welding-brazing and interface analysis of lap joint Ti–6Al–4V and aluminum by plasma arc welding. J Manuf Process2021; 61: 396–407.
8.
GuoSZhouQPengY, et al.Study on strengthening mechanism of Ti/Cu electron beam welding. Mater Des2017; 121: 51–60.
9.
MöllerFGrdenMThomyC,et al.Combined laser beam welding and brazing process for aluminium titanium hybrid structures. Phys Procedia2011; 12: 215–223.
10.
RaoASReddyGMPrasadKS. Microstructure and tensile properties of dissimilar metal gas tungsten arc welding of aluminium to titanium alloy. Mater Sci Technol2011; 27: 65–70.
11.
KotaPKAmoghTKVigneshRV,et al.Joining of cast iron and phosphor bronze through liquid–solid interaction: effect of Ni and Cu coating on interfacial microstructures and mechanical properties of bimetallic composites. Int J Met2023. doi: 10.1007/s40962-023-00995-x
12.
PadmanabanRBalusamyVVaira VigneshR. Effect of friction stir welding process parameters on the tensile strength of dissimilar aluminum alloy AA2024-T3 and AA7075-T6 joints. Materwiss Werksttech2020; 51(1): 17–27.
13.
FronczekDMWojewoda-BudkaJChulistR, et al.Structural properties of Ti/Al clads manufactured by explosive welding and annealing. Mater Des2016; 91: 80–89.
14.
DresslerUBiallasGMercadoUA. Friction stir welding of titanium alloy TiAl6V4 to aluminium alloy AA2024-T3. Mater Sci Eng A2009; 526: 113–117.
15.
NgHPPrzybillaTSchmidtC, et al.Asymmetric accumulative roll bonding of aluminium–titanium composite sheets. Mater Sci Eng A2013; 576: 306–315.
16.
PantelakisSTserpesKI. Adhesive bonding of composite aircraft structures: challenges and recent developments. Sci China Phys Mech Astron2014; 57: 2–11.
17.
DunfordDVWisbeyA. Diffusion bonding of advanced aerospace metallics, vol. 314. Farnborough, Hants, UK: Materials and Structures Department, Defence Research Agency, 1993, pp.39–50.
18.
GovindarajuMBalasubramanianK. Manufacturing copper-stainless steel composite tube by pressure bonding. In: Brazing and soldering 2012: IBSC proceedings of 5th international conference. ASM International, Las Vegas, Nevada, USA, 2012, p.364.
19.
LeeHYoonJYooJ. A study on solid state welding of aerospace materials. 2018; 762: 343–347.
20.
PrescottRGrahamMJ. The formation of aluminum oxide scales on high-temperature alloys. Oxid Met1992; 38: 233–254.
21.
AtasoyEKahramanN. Diffusion bonding of commercially pure titanium to low carbon steel using a silver interlayer. Mater Charact2008; 59: 1481–1490.
22.
BarrenaMIMatesanzLde SalazarJMG. Al2O3/Ti6Al4V diffusion bonding joints using Ag-Cu interlayer. Mater Charact2009; 60: 1263–1267.
23.
AkcaEGurselA. Influences of argon gas shielding on diffusion bonding of Ti–6Al–4V alloy to aluminum. Rev Metal2017; 53: 88.
24.
ZuruziASLiHDongG. Effects of surface roughness on the diffusion bonding of Al alloy 6061 in air. Mater Sci Eng A1999; 270: 244–248.
25.
KarfoulMKTatlockGJ. Interfacial processes during diffusion welding of titanium alloy/aluminium couples under ambient atmosphere. Weld World2019; 63: 841–849.
26.
FukutomiHNakamuraMSuzukiT, et al.Void formation by the reactive diffusion of titanium and aluminium foils. Mater Trans2000; 41: 1244–1246.
27.
LiBChenZHeW, et al.Materials characterization effect of titanium grain orientation on the growth of compounds at diffusion bonded titanium/steel interfaces. Mater Charact2019; 148: 243–251.
28.
AssariAHEghbaliB. Solid state diffusion bonding characteristics at the interfaces of Ti and Al layers. J Alloys Compd2019; 773: 50–58.
29.
WeiYAipingWGuishengZ,et al.Formation process of the bonding joint in Ti/Al diffusion bonding. Mater Sci Eng A2008; 480: 456–463.
30.
KotaPKMyilsamyGRamalingamVV. Metallurgical characterization and mechanical properties of solid–liquid compound casting of aluminum alloy: steel bimetallic materials. Met Mater Int2021; 28: 1416–1422.
31.
AlhazaaANKhanTI. Diffusion bonding of Al7075 to Ti–6Al–4V using Cu coatings and Sn–3.6Ag–1Cu interlayers. J Alloys Compd2010; 494: 351–358.
32.
ChangSYTsaoLCLeiYH, et al.Journal of materials processing technology brazing of 6061 aluminum alloy/Ti–6Al–4V using Al–Si–Cu–Ge filler metals. J Mater Process Technol2012; 212: 8–14.
33.
JiangweiRYajiangLTaoF. Microstructure characteristics in the interface zone of Ti/Al diffusion bonding. Mater Lett2002; 56: 647–652.
34.
SamavatianMHalvaeeAAmadehAA,et al.An investigation on microstructure evolution and mechanical properties during liquid state diffusion bonding of Al2024 to Ti–6Al–4V. Mater Charact2014; 98: 113–118.
35.
AssadiHShirzadiAAWallachER. Transient liquid phase diffusion bonding under a temperature gradient: Modelling of the interface morphology. 2001; 49: 31–39.
36.
EnjyoTIkeuchiKKanaiM,et al.Diffusion welding of aluminum to Titanium. Trans JWRI1977; 6: 123–130.
37.
AuthorT, et al.Effects of insert-metals on diffusion welding of aluminum to Titanium. Trans JWRI1977; 6: 251257.
38.
AlHazaaAKhanTIHaqI. Transient liquid phase (TLP) bonding of Al7075 to Ti–6Al–4V alloy. Mater Charact2010; 61: 312–317.
39.
AnbarzadehASabetHAbbasiM. Effects of successive-stage Transient Liquid Phase (S-TLP) on microstructure and mechanical properties of Al2024 to Ti–6Al–4V joint. Mater Lett2016; 178: 280–283.
40.
AfghahiSSSEkramiAFarahanyS,et al.Fatigue properties of temperature gradient transient liquid phase diffusion bonded Al7075-T6 alloy. Trans Nonferrous Met Soc China (English Ed)2015; 25: 1073–1079.
41.
KunduSChatterjeeS. Effect of temperature on formation of reaction products and strength properties of titanium and stainless steel joints using copper interlayer. Mater Sci Technol2007; 23: 368–373.
42.
AnandMSMurarkaSPAgarwalaRP. Diffusion of copper in nickel and aluminum. J Appl Phys1965; 36: 3860–3862.
43.
NakagawaKKanadaniTAnthonyL,et al.Microstructural changes at the initial stage of precipitation in an aluminum–silicon alloy. Mater Trans2005; 46: 779–783.
44.
FujiAAmeyamaKNorthTH. Influence of silicon in aluminium on the mechanical properties of titanium/aluminium friction joints. J Mater Sci1995; 30: 5185–5191.
45.
Van BoggelenJWKEskinDGKatgermanL. First stages of grain coarsening in semi-solid Al–Cu alloys. Scr Mater2003; 49: 717–722.
46.
SpringerHKostkaAdos SantosJF,et al.Influence of intermetallic phases and Kirkendall-porosity on the mechanical properties of joints between steel and aluminium alloys. Mater Sci Eng A2011; 528: 4630–4642.
47.
NakajimaH. The discovery and acceptance of the Kirkendall effect: The result of a short research career. Jom1997; 49: 15–19.
48.
KenevisiMSKhoieSMM. An investigation on microstructure and mechanical properties of Al7075 to Ti–6Al–4V transient liquid phase (TLP) bonded joint. Mater Des2012; 38: 19–25.
49.
TavoosiM. The Kirkendall void formation in Al/Ti interface during solid–state reactive diffusion between Al and Ti. Surf Interface2017; 9: 196–200.
50.
KenevisiMSMousavi KhoieSM. An investigation on microstructure and mechanical properties of Al7075 to Ti–6Al–4V transient liquid phase (TLP) bonded joint. Mater Des2012; 38: 19–25.
51.
ZobacOKroupaAZemanovaA,et al.Experimental description of the Al–Cu binary phase diagram. Metall Mater Trans A Phys Metall Mater Sci2019; 50: 3805–3815.
52.
OkamotoH. Phase diagram for binary alloys. Desk Hand B2000; 315: 46.
53.
PengLMWangJHLiH, et al.Synthesis and microstructural characterization of Ti–Al3Ti metal-intermetallic laminate (MIL) composites. Scr Mater2005; 52: 243–248.
54.
WangPChenZHuC, et al.Effects of annealing on the interface microstructures and mechanical properties of hot roll bonded Ti6Al4V/AA6061 clad sheets. J Mater Res Technol2020; 9: 11813–11825.
55.
MaoAZhangJYaoS, et al.The diffusion behaviors at the Cu–Al solid–liquid interface: A molecular study. Results Phys2020; 16: 1–9.
56.
ChenSKeFZhouMBaiY. Atomistic investigation of the effects of temperature and surface roughness on diffusion bonding between Cu and Al. Acta Mater2007; 55(9): 3169–3175.
57.
LiCLiDTaoX, et al.Molecular dynamics simulation of diffusion bonding of Al–Cu interface. Model Simul Mater Sci Eng2014; 22(6): 65013.
58.
EslamiPTaheriAK. An investigation on diffusion bonding of aluminum to copper using equal channel angular extrusion process. Mater Lett2011; 65(12): 1862–1864.
59.
LiYLuTCaoL, et al.Diffusion bonding of Mg/Cu alloy with Zn interlayer metal. Adv Mater Res2014; 911: 168–172.
60.
IlangovanS. Study of effect of cooling rate on mechanical and tribological properties of cast Al–6.5Cu aluminum alloy. Int J Res Eng Technol2014; 03: 62–66.
61.
GhoshSKChatterjeeS. On the direct diffusion bonding of titanium alloy to stainless steel. Mater Manuf Process2010; 25: 1317–1323.
62.
SimõesSVianaFRamosAS, et al.Reaction-assisted diffusion bonding of TiAl alloy to steel. Mater Chem Phys2016; 171: 73–82.
