Enhanced mechanical properties of Ti6Al4V alloy fabricated by laser additive manufacturing under static magnetic field

Figures & data

Figure 1. (a) Schematic showing the solidification process of L-DED under a 0.55 T transverse SMF, where (c) the thermoelectric current and thermoelectric magnetic force are illustrated in the solidification front. (b) Distribution of magnetic field intensity. (d) and (g) OM images; (e) and (h) β grains microscopy images; (f) and (i) Histograms of β grain size.

Figure 2. (a) and (b) XRD 001 pole figures (PFs) of the β phase in samples without (a) and with (b) SMF. (c) and (d) XRD 110 PFs of the β phase in samples without (c) and with (d) SMF. (e) and (f) Standard poles of <100> and <110> in 001 PFs (e) and 110 PFs (f). (g) Volume percent of preferred orientations of samples without and with SMF along (001) <100> fiber texture.

Figure 3. Multi-scale microstructure characterizations of Ti64 sample without (a–d) and with (e–h) SMF: (a, e) SEM-BSE; (b, f) EBSD inverse pole figures (IPFs); (c, g) (0002) α PFs of α phase to corresponding (b) and (f); (d, h) TEM-DF observations.

Figure 4. (a) Stress-strain curves of the samples without and with SMF performed on transverse (V*) and longitudinal (H*) directions, respectively. (b) Comparison of UTS vs. ε_f of Ti64 with related studies [6,9,22–27]. (c, d and g, h) Fracture morphology of samples without and with SMF; (e, f and i, j) TEM-DF observations of the fractured longitudinal samples without (e, f) and with (i, j) SMF, which is located 1 mm below the fracture.

Table 1. Tensile behavior of L-DED Ti64 without or with SMF.

Conditions		YS (MPa)	UTS (MPa)	εf (%)
V*	Without SMF	782.3 ± 18.2	869.6 ± 23.3	11.2 ± 1.1
	With SMF	775.0 ± 0.8	864.4 ± 13.6	12.6 ± 1.7
H*	Without SMF	913.1 ± 63.0	1030.0 ± 73.5	3.4 ± 0.7
	With SMF	788.5 ± 31.5	920.6 ± 25.4	10.8 ± 2.8

Table 2. Physical parameters of Ti-6Al-4V.

Parameters	Value	Unit
Operational temperature, T	1968	K
Electrical conductivity in solid-state, σS	0.73 × 10^6	Ω^−1·m^−1
Electrical conductivity in liquid-state, σL	0.66 × 10^6	Ω^−1·m^−1
Seebeck coefficient in solid, SS*	−0.1	µV/K
Seebeck coefficient in solid, SL*	−2	µV/K
Intensity of magnetic field, B	0.55	T
Temperature gradient, ∇T	1 × 10^5	K/m

*Due to the high melting point of Ti-alloy, the Seebeck coefficient is not only unmeasurable but has never been reported. Therefore, the parameters of Al-alloy are used to estimate the TEM force [32], which are paramagnetic materials as well as Ti-alloys.

Figure 5. (a) and (c) EBSD IPFs of GBs α. (b) and (d) Reconstructed EBSD IPFs of β in samples. (e) and (f) 0002 PFs of the GBs α corresponding to (a) and (c). (g) and (h): 110 PFs of the reconstructed β phase corresponding to (b) and (d).

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