# Advanced Metal Matrix Nanocomposites
## 3 Reinforcing Agents
Nanodiamonds were first synthesized in the USSR in the 1960s [87]. However, it took until the 1990s to develop some of applications capitalizing on their extremely hard nature with a very high Young's modulus. They have special optical properties and can be fluorescent. In addition to many possibilities in biological applications as biomarkers or drug delivery agents, they can also be used as reinforcing components in nanocomposites. Nanodiamonds can be released when biodegradable magnesium alloys degrade. They can serve as biomarkers with a fluorescent surface or can be visualized in imaging processes using their magnetic properties; nanodiamonds are the least cell-toxic carbon-based nanomaterials [88; 89]. An aluminum-based composite material with 0.2 wt% nanodiamonds has been explored for its mechanical properties [90]. A powder mixture of aluminum powder and nanodiamonds is mixed and hot-pressed. As a second material, an Al-7 Si alloy was mixed with nanodiamonds using ultrasound and its properties were examined; apparently, Al\({}_{4}\)C\({}_{3}\) is formed in the hot-pressed nanocomposite during the manufacturing process with significantly improved mechanical properties including yield strength, tensile strength, and Young's modulus. These properties are also significantly improved in the cast material. Using a powder metallurgy method, [PERSON] et al. have reinforced pure magnesium with nanodiamonds and investigated the suitability of the MMNC as degradable implant material [19]; the corrosion rate being the focus of investigations. It turned out that magnesium with 1, 3, and 5 wt% nanodiamonds show a decreasing degradation rate with increasing particle content. The corrosion \begin{table}
\begin{tabular}{c c c c c} \hline
**Base** & **Carbide** & **Nitride** & **Boride** & **Oxide** \\ \hline Aluminium & & & AlN & & Al\({}_{2}\)O\({}_{3}\) \\ Antimony & & & & Sb\({}_{2}\)O\({}_{3}\) \\ Boron & B\({}_{4}\)C & BN & & & Br\({}_{2}\)O\({}_{3}\) \\ Bismuth & & & & & Bi\({}_{2}\)O\({}_{3}\) \\ Cerium & & & & CoO\({}_{2}\) \\ Chromium & CrC & CrN & CrB & CrO\({}_{4}\) Cr\({}_{2}\)O\({}_{3}\) \\ Cobalt & & & & CoO\({}_{2}\)O\({}_{3}\), Co\({}_{3}\)O\({}_{4}\) \\ Copper & & & & CuO \\ Dysprosium & & & & Dy\({}_{2}\)O\({}_{3}\) \\ Etbium & & & & Er\({}_{2}\)O\({}_{3}\) \\ Europium & & & & Eu\({}_{2}\)O\({}_{3}\) \\ Gadolinium & & & & Gd\({}_{2}\)O\({}_{3}\) \\ Hafnium & HFC & HN & & HfO\({}_{2}\) \\ Indium & & & & In\({}_{2}\)O\({}_{3}\) \\ Iron & & & & Fe\({}_{3}\)O\({}_{4}\), Fe\({}_{2}\)O\({}_{3}\) \\ Lanthanum & & & LaB\({}_{6}\) & La\({}_{2}\)O\({}_{3}\) \\ Magnesium & & & & MgO \\ Manganese & & & & MnO\({}_{2}\), MnO\({}_{3}\), Mn\({}_{2}\)O\({}_{3}\) \\ Molybdenum & MoC, Mo\({}_{2}\)C & MoN, Mo\({}_{2}\)N & MoB, Mo\({}_{2}\)B & MoO\({}_{3}\) \\ Needymium & & & & Nd\({}_{2}\)O\({}_{3}\) \\ Nickel & & & & NiO, Ni\({}_{2}\)O\({}_{3}\) \\ Nibobium & & & & Nb\({}_{2}\)O\({}_{5}\) \\ Prasodymium & & & & Pr\({}_{6}\)O\({}_{11}\) \\ Samarium & & & & Sm\({}_{2}\)O\({}_{3}\) \\ Silicon & SiC & Si\({}_{3}\)N\({}_{4}\) & & SiO\({}_{2}\) \\ Tantalum & TaC & TaN & & Ta\({}_{2}\)O\({}_{5}\) \\ Terbium & & & & Tb\({}_{2}\)O\({}_{7}\) \\ Tin & & & & SnO\({}_{2}\) \\ Titanium & TIC & TiN & TiB\({}_{2}\) & TiO\({}_{2}\) \\ Tungsten & WC, W\({}_{2}\)C & WN, W\({}_{2}\)N & WB, W\({}_{2}\)B & WO\({}_{3}\) \\ Vanadium & & & & VO, V\({}_{2}\)O\({}_{3}\), V\({}_{2}\)O\({}_{5}\) \\ Yttrium & & & & Y\({}_{2}\)O\({}_{3}\) \\ Yttterbium & & & & Yb\({}_{2}\)O\({}_{3}\) \\ Zinc & & & & ZnO \\ Zirconium & ZrC & ZrN & ZrB\({}_{2}\) & ZrO\({}_{2}\) \\ \hline \end{tabular}
\end{table} 
Table 2: Commercially available nanoparticles. rate of the MMNC with 5 wt% particles was 4.5 times lower than that of pure magnesium. The nanodiamonds do not reduce the cell viability. CNTs are coiled graphene, which in turn are single layers of graphite, i.e., two-dimensional structures of hexagonally-arranged carbon atoms. Each carbon atom is covalently bonded to three other carbon atoms in the plane and, thus, the four-bondedness of the carbon is not fulfilled.