Multi-wire arc additive manufacturing of TC4/Nb bionic layered heterogeneous alloy: Microstructure evolution and mechanical properties

The performance improvement of wire arc additive manufacturing component relies on structural innovation and tailored printing, and the naturally optimized structure can provide inspiration for design and manufacturing. In this work, a layered TC4/Nb multi-material alloy component inspired by the biological structure of the Cryso-mallon squamiferum shell was designed and fabricated by multi-wire arc additive manufacturing (MWAAM). The interfacial reaction, phase composition, microstructure evolution, crystal growth, mechanical properties and crack propagation of MWAAM-processed bionic heterogeneous TC4/Nb multi-material alloy component were investigated by EDS, SEM, EBSD and mechanical tester. The results indicated that the good metallurgical bond was formed between the different layers of MWAAM TC4/Nb multi-material alloy sample. The Ti/Nb multi -material alloy component was mainly composed of & alpha;-Ti, & beta;-Ti and (Nb, Ti) solid solution phases. The morphology of phase underwent a continuous transformation process from TC4 layer to G1 layer with the in-crease of Nb content: Lamellar & alpha; + & beta; & RARR;Thin lamellar & alpha; + Short rod & alpha; + & beta; & RARR; Acicular & alpha; + & beta; & RARR; Thin acicular & alpha; + & beta;. In addition, the grain size of TC4/Nb multi material alloy component from TC4 layer to G2 layer gradually from 3.534 & mu;m decreased to 2.904 & mu;m with the increase of Nb content. The microhardness of TC4/Nb multi-material alloy from TC4 layer to G2 layer ranged from 404.04 HV to 245.23 HV. The relatively high compression strength and ultimate tensile strength of TC4/Nb multi-material alloy sample were 2162.64 & PLUSMN; 26 MPa and 663.39 MPa, and corresponding strain were 31.99% and 17.77%, respectively. The excellent mechanical behavior was mainly contributed to the excellent combination of gradient transition of grain size and microstructure evolution be-tween layers. Crack propagation was mainly dominated by crack deflection and multistage cracking during the tensile test process. The strength of TC4 layer was the highest than G1 and G2 layer in the TC4/Nb multi-material alloy component.

Automated summary

Inspired by the biological structure of the Cryso-mallon squamiferum shell, a layered TC4/Nb multi-material alloy component was designed and fabricated using multi-wire arc additive manufacturing (MWAAM). The results showed that a good metallurgical bond was formed between the different layers, and the component exhibited excellent mechanical properties due to the gradient transition of grain size and microstructure evolution between layers.