**Author details**

**Composite Resulting microstructure Remarks** 

Cu + WC by SLM \_ \_

Co + WC Partial dissolution of WC

**Cu-matrix composites**

204 New Trends in 3D Printing

**Co-matrix composites**

Co + TiC and CaF2 by laser cladding

Ti-Nb-Zr-Ta + TiB \_ Enhanced wear resistance for

Cu + WC/Co by DMLS \_ Hardness and strength

and precipitation of complex

Data from **Table 2** highlight the importance of carefully selecting the reinforcing phase of the composites in view of not only the desired properties and application but also considering the

**•** Carbides constitute the most popular reinforcement in combination with a wide range of metallic materials. However, in some occasions, they may give rise to deleterious reaction products such as the brittle Al4C3 in Al matrix composites or chromium carbides that may compromise the corrosion resistance of stainless steels. A careful optimisation of the laser additive manufacturing processing parameters may be necessary in order to avoid the

**•** Nitrides and borides are interesting alternative to carbides, in view of their generally good

**•** As a general rule, oxides appear much less promising for use as reinforcing phase in MMCs fabricated by laser additive manufacturing. Oxide particles may easily decompose during laser irradiation, and they present a strong tendency to dissolve in the melt pool and reprecipitate as a detrimental oxide skin that would compromise the good cohesion of successive additive-manufactured layers. A notable exception is the addition of rare earth oxide nanoparticles that act as very potent microstructural refiner, with beneficial effects on

**•** Nanocomposites with enhanced properties have been successfully fabricated by laser additive manufacturing. However, specific procedures are necessary in order to avoid the processability issues related with the high tendency of nanoparticles to agglomerate and with their low flowability. For the production of ex situ MMCs, a nanostructured powder

carbides [5, 80–82]

**Table 2.** Synoptic table of representative MMCs fabricated by laser additive manufacturing.

compatibility of the reinforcement with the metallic matrix:

formation of these undesirable reaction products.

chemical stability and of their excellent mechanical properties.

the mechanical and corrosion properties of the MMCs.

use in femoral implant [98, 99]

combined with good electrical and thermal conductivity [76–

Applications in cutting tools [5,

78]

80–82]

\_ Self-lubricating MMCs [83]

Anne I. Mertens\* and Jacqueline Lecomte-Beckers

\*Address all correspondence to: anne.mertens@ulg.ac.be

University of Liege, Aerospace and Mechanical Engineering, Metallic Materials Science, Liège, Belgium
