## 3 Results
### DED Additive Manufacturing
#### 3.2.4 Magnetic Properties  
Samples B, C, F, G and K of Table 6 were \(>\)3 mm diameter consistently across their length which enabled magnetic property testing of these full-Co samples after MA and FHT, as shown in Table 9. Multiple samples were taken from samples B and C due to their length and are listed accordingly. The increased diameter of the built cylinders permitted equiaxed, fine grain \"skin\" removal during cylinder fabrication, potentially improving magnetic properties. However, it should be noted that the cylinder microstructure going into the MA and FHT process consisted of the microstructure shown in Figure 9. Past investigations have shown how sensitive the FHT optimization and resulting magnetic properties are to the processing steps and the starting microstructure for essentially all cast, sintered, and/or DED alnico samples. Thus, the limited number of DED samples for a given set of AM processing parameters prevented extensive optimization [16; 28]. A limited MA optimization (+5 \({}^{\circ}\)C) was attempted (with a constant FHT) for the sample listed as C-2, compared to sample C-1. The cast sample also underwent an optimization test (\(-\)5 \({}^{\circ}\)C). For the full-Co, the highest remanence value was seen for the B-2 sample and is comparable to the sintered samples of the same powder and higher than that of the (isotropic) cast sample. This improved remanence value is typically an indication of increased texturing of the build microstructure, but this was not obvious in the EBSD results, when compared to the results from sample C in Figure 7; Figure 8. The highest coercivity value of the DED samples was also the B-2 sample at 2110 Oe, slightly exceeding the coercivity of the baseline sintered samples, yet lower than the cast sample. Thus, the highest energy product of the DED samples was also the B-2 sample at 4.90 MGOe, improving upon the sintered sample and cast energy product of 4.50 MGOe and 4.69 MGOe, respectively. The rest of the full-Co DED samples in Table 9 were close in remanence, coercivity and energy product (with the exception of sample G), indicating very small deviation in magnetic properties as a function of DED processing parameters. This finding is very beneficial for AM processing of complex geometries and indicates a high buildability of the alnico material. \begin{table}
\begin{tabular}{c c} \hline \hline
**Sample (MA time (min)/MA temperature (\({}^{\circ}\)C)** & **Density (g/cm\({}^{3}\))** \\ \hline
8/830 & 7.26 \\
8/850 & 7.24 \\
8/870 & 7.26 \\
4/830 & 7.20 \\
4/850 & 7.26 \\
4/870 & 7.27 \\
1/830 & 7.25 \\
1/850 & 7.20 \\
1/870 & 7.26 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Geometrical density of Co-lean EBM/PBF alnico post machined cylinders. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Br (kG)** & **HcJ (Oe)** & **BHmax (MGOe)** & **Ms (kG)** \\ \hline Sintered (12 h) & 7.36 & 2061 & 4.50 & 10.60 \\ Cast & 6.60 & 2428 & 4.69 & 10.40 \\ B-2 & 7.35 & 2110 & 4.90 & 10.87 \\ B-3 & 6.86 & 2022 & 4.09 & 10.22 \\ C-1 & 6.75 & 2034 & 4.06 & 10.19 \\ C-2 & 6.81 & 2037 & 4.12 & 10.18 \\ F & 6.79 &Similar to the full-Co, the Co-lean as-built DED samples were \(>\)3 mm diameter rough cylinders (see Figure 6 and Table 7) consistently along their length which enabled machining to the proper dimensions for magnetic property testing after MA and FHT, as shown in Table 10. Unlike the full-Co, the diameters of the as-built parts were smaller than that of the full-Co. This slightly decreased diameter resulted in the fine grain \"skin\" (see Figure 10) to remain within the final machined cylinder samples, potentially impacting magnetic properties. However, it should be noted that the cylinder microstructure going into the MA and FHT process consisted of the microstructure shown in Figure 12, showing similar grain growth behavior to the full-Co DED samples. Two cylinders were extracted from each as-built specimen, and similar to the full-Co composition, there was limited capability to explore MA and FHT parameters with these Co-lean samples.