## 3 Results and Discussion
### Mechanical Properties  
Figure 7 shows the results of measuring Vickers hardness for four types of TMF \(\beta\) alloys manufactured according to the alloy composition and process method. In the case of the P/M alloy, it was determined that the hardness values of TMF 34 P/M and TMF 54 P/M were 397.5 Hv and 396.5 Hv, respectively, which slightly decreased when the Mo content increased. In general, it is known that as the Mo content increases, the hardness value increases due to the solid-solution strengthening effect [35], but when the Mo content increases, the hardness value increases due to the decrease in the thickness of Widmanstatten \(\alpha\)-lath and the pore fraction increases (2.1% \(\rightarrow\) 3.5%). As a result, the effect of decreasing the hardness value was largely affected and it is considered that the hardness value of TMF 54 P/M was similar to the hardness value of TMF 34 P/M.  
Figure 6: IPF maps of prior \(\beta\) grains reconstructed by misorientation criterion and denoising method (**a**) TMF 34 P/M and (**b**) TMF 54 P/M.  
Figure 7: Vickers hardness of TMF 34 and TMF 54 alloys.  
In addition, in the case of the I/M alloy, the hardness values of TMF 34 I/M and TMF 54 I/M are 422.1 Hv and 414.8 Hv, respectively, where the hardness value of TMF 34 I/M is slightly higher than that of TMF 54 I/M. In the case of TMF 34 I/M, it is an \(\alpha+\beta\) lamellar Widmanstatten microstructure. In the case of TMF 54 I/M, it is a relatively soft \(\alpha\)-phase precipitated in the equiaxed \(\beta\) grain. Therefore, in the case of the I/M alloy, the hardness value of TMF 34 I/M was measured higher than the hardness value of TMF 54 I/M. In addition, the P/M alloy has a hardness value lower than that of I/M with the same composition and the hardness of the P/M alloy is decreased due to pores in the P/M alloy. Thus, it is considered that the hardness value of the P/M alloy is lower than that of the ingot alloy.  
The tensile stress-strain curves obtained from the room temperature tensile test conducted on four types of the TMF beta alloys are shown in Figure 8 and the tensile characteristic values (yield strength, ultimate tensile strength, and elongation) measured from the curve are shown in Table 1. All P/M alloys were fractured before the yield point, and mechanical strength and elongation were measured lower than those of the I/M alloys. This shows that the fracture occurred before the yield point due to pores and the fracture surface shows a cleavage fracture form in all P/M alloys. It can be seen that cracks started from these pores (Figure 9a,b). In addition, the ultimate tensile strength of TMF 54 P/M was 815.27 MPa, which was higher than that of TMF 34 P/M. The cause is considered to be the influence of the prior \(\beta\) grain size and the strength increases according to the Hall-Petch equation because the prior \(\beta\) grain size is small [36].  
In the case of the I/M alloy, TMF 54 I/M has the equiaxed \(\beta\) grain with a relatively soft microstructure. As mentioned above, in the equiaxed microstructure, it is reported that the slips are strengthened due to the interference in the movement caused by the \(\alpha\) phases precipitating inside the equiaxed \(\beta\) grain, and not only slips but also twins act as a deformation mechanism, contributing to the increase in elongation [34]. Therefore, the TMF 54 I/M alloys with the equiaxed microstructure represents higher elongation than the TMF 34 I/M alloys with \(\alpha+\beta\) lamellar Widmanstatten microstructure. As shown in Figure 9c,d, some dimple structures, which indicate a ductile fracture behavior, were observed on the fracture surface of TMF 54 I/M. However, in the case of TMF 34 I/M, the cleavage fracture surface, a characteristic of brittle fracture behavior, was observed.