Page 54 - MSAM-1-4

Materials Science in Additive Manufacturing LPBF of Mg and its bio-applications

Table 1. Comparison of physical performance between Mg alloys and other bone implants
Materials Density (g/cm ) Modulus (GPa) Compressive yield (MPa) Elongation (%)
3
Human bone [12,16,17] 1.8 – 2.1 10 – 30 130 – 180 3 – 6
Mg alloys [16,17] 1.79 – 2.0 37.5 – 65 70 – 140 2 – 11
Ti alloys [17,18] 4.2 – 4.5 79 – 110 795 – 908 6 – 16
Co alloys [17,18] 8.3 – 9.2 220 – 230 450 – 1500 5 – 30
316 L steel [17,18] 8.0 193 172 – 690 12 – 40
Tantalum [17,18] 16.7 188 – 190 138 – 345 1 – 30
Hap [18,19] 3.1 80 – 110 0.03 – 0.3 /
TCP [18,19] / 24 – 39 2 – 3.5 /
Fe alloys [17-19] 7.8 – 7.9 200 – 205 170 – 690 12 – 40

material. Due to its characteristics, SLM can be effectively
applied as a prospective production technique for valuable
materials and components, through cutting down the
cost and lead time of fabrication and reducing the loss of
material. Therefore, it has attracted increasing interest and
attention in fabricating biodegradable Mg-based implants.
In 2011, Ng et al. used the SLM process to prepare
[33]
pure Mg, which was the first report about the Mg alloy
for custom biomedical implants. Since then, Mg and its
alloys for the degradable implants has become hotspot
research in biomedical field. In this review, we present a
systematic analysis and discussion on the recent literature
on LPBF-processed Mg alloy. In addition, the effect
Figure 1. The advantages of Mg implants and its clinical applications.
of the comprehensive powder properties, parameters
optimization, and post-treatment on their mechanical
the process has an extended processing cycle and low and degradable properties will be highlighted, along with
material utilization. Unfortunately, these methods cannot the current challenges in LPBF-processed Mg alloys. The
easily control the pore size to obtain complex geometric review also presents insights into the future of Mg alloys
shapes. Additive manufacturing (AM), commonly known and their use in biomedical applications.
as three-dimensional (3D) printing, is a manufacturing
technology that integrates computer-aided design, 2. LPBF-processed Mg alloys
material processing, and molding technologies and uses
digital model files as a basis. Meanwhile, through software The fabrication of Mg and its alloys through LPBF is deemed
and CNC systems, special materials are stacked layer by to be extremely challenging. On the one hand, due to the
layer in accordance with extrusion, sintering, melting, light inherent inflammability and explosiveness, the preparation
curing, or spraying to fabricate block parts . Compared conditions of Mg powders are extremely demanding. On
[31]
with traditional manufacturing technology, AM could the other hand, low evaporation temperature and high
provide a reliable way to obtain personalized complex vapor pressure of Mg tend to trigger micro-crack during
3D structures, which can efficiently and reliably replicate LPBF processing, causing poor structural integrity of
anatomical morphology related to tissues and organs. parts. Thus, until now, there is no relevant report on LPBF-
It could prepare precisely controlled pore structure to processed ultrapure Mg (>99.9%). A great deal of current
meet the personalized customization needs of patients. research on Mg prepared by LPBF has focused on its alloys.
In particular, LPBF is commercially known as selective This is due to their good workability and low risk.
laser melting (SLM), which uses metallic and non-metallic 2.1. Preparation of the feedstock
powders as the raw material . In contrast to other AM
[32]
technologies, SLM can process a very wide variety of It is well known that LPBF is a typical powder metallurgy
materials. In addition, it is possible to recycle and reuse technology. Powder properties are an essential part of
unmelted metal powder, which allows the efficient use of the the LPBF industry chain. The powder should possess a

Volume 1 Issue 4 (2022) 3 https://doi.org/10.18063/msam.v1i4.24