## 5 Conclusions  
In this research, HT methods for hybrid components were investigated, especially their impact on the microstructure and mechanical strength of hybrid MIM/PBF 316L components. A special HIP treatment was investigated for overcoming slack microstructures and incompatibilities between MIM and L-PBF processes when producing hybrid components. The HIP treatment allows the HCM process to produce hybrid components with tailored and consistent mechanical and chemical properties to meet the technical requirements of end use applications. Based on the obtained experimental results, the following conclusions were made:  
1. Conventional HT, such as air-quenching was found to introduce a brittle phase precipitation in hybrid components. Therefore, air-quenching impairs the hybrid components' strength by decreasing the elongation and especially their UTS below the materials standards.
2. High pressure in combination with higher temperatures reduce porosity in the MIM preforms, in contrast to conventional HT which enlarges the pores significantly compared to the primary microstructure. Thus, minimising and eliminating defects and porosity accumulation, due to gas and residues expansion.
3. The 316 L air-quenched samples were found to have no molybdenum content and moreover, showed a lower corrosion resistance compared to the HIP samples. In particular, the HIP treatment led to a greater pitting resistance, while demonstrating a retention of the high Mo concentration (wt \(\sim\)3%) and thus making HIP samples suitable for corrosive environments.
4. The HIP treatment was found to increase the hybrid components' strength compared to as-built ones by \(\sim\)68 and \(\sim\)11% in YS and UTS, respectively. These mechanical properties improvements were attributed to the further densification of the lattice, the reduced inherent defects and diffusions compared to the primary or air-quenched microstructure.  
Another beneficial effect of the HIP treatment was the resulting equiaxed grains that removed any heterogeneities and minimised any porosity in the bulk, whilst maintaining a ductility rate higher to that of air-quenched hybrid components.  
The HIP treatment reduced the probability of brittle fracture or premature failure with the deformation and recrystallization within the lattice, due to the applied high temperature and pressure. As a result of the higher temperature and pressure, both sections of the hybrid components benefit from the minimised porosity, leading to a higher interface quality and consequently superior strength of the hybrid parts that conform to the results reported in the literature.  
The research showed clearly that the HIP treatments of hybrid components can address some significant shortfalls of the HCM process when combined with traditional heat treatments and thus, to meet the technical requirements for a range of applications. This can be achieved by applying a well-known and proven functional treatment.  
Conceptualization, A.M.; methodology, A.M.; validation, A.M. and D.L.; investigation; formal analysis, A.M. and A.M.; resources, A.M., J.M., D.V. and P.P.; writing--original draft preparation, A.M.; writing--review and editing, A.M., D.L. and R.M.R.; visualization, A.M.; supervision, S.D., K.E. and D.I.W.; funding acquisition, S.D. and D.I.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded from the European Union's Horizon 2020 research and innovation programme, under grant agreement no. 723826 MAESTRO.  
Not applicable.  
The authors would like to thank the Manufacturing Technology Centre (MTC) for the financial support of [PERSON]'s PhD research.  
The authors declare no conflict of interest.