**5. General remarks**

*Magnesium - The Wonder Element for Engineering/Biomedical Applications*

τ*bond*

Where *m* represents the strength coefficient of the bond, τ*bond* is the strength of

TLP diffusion bonding is a heavily time-dependent process with the duration of each stage contributing to the length of time required to achieve bond strength. Several models have been developed based on Fick's second law that seeks to predict the duration of each stage of the TLP bonding process. The most notable of these models was proposed by Zhou et al. [54]. Experimental research on TLP bonding of

<sup>τ</sup>*<sup>b</sup>* (3)

*m* = \_\_\_\_

the bond and <sup>τ</sup>*b* is the strength of the base metal.

**Interlayer Temperature** 

**(C)**

*condition 10 minutes at 500°C and 0.2 MPa (B) EDS analysis of the highlighted region.*

**Pressure (MPa)**

*(A) TLP bonding of Mg-AZ31) and Al-1100 using a Cu coating containing nano-Al2O3 particles and bonding* 

Mg AZ31 Cu foil 530 2.0 30 70.2 0.852 [3]

**Time (minutes)**

520 0.5 30 64.0 0.771 [51]

580 1.0 15 78.0 0.934 [51]

Ni coatings 520 8.0 20 46.2 0.557 [49]

Cu coatings 520 0.5 30 41.0 0.482 [2]

Ni coating 540 0.2 20 50 0.602 [46]

Cu/Al2O3 500 0.2 10 20.4 0.36 Current

**Shear strength (MPa)**

*m* **Reference**

work

*4.2.2 Bonding time and temperature*

**96**

**Table 1.**

**Bonding system**

**Figure 15.**

Mg-AZ31 similar bonding

Mg-AZ31 similar bonding

Mg-AZ31 similar bonding

Mg-AZ31 and Ti-6Al-4V

Mg-AZ31 and Ti-6Al-4V

Mg-AZ31 and Al100 Cu coatings with Sn foil

Cu coatings with Sn foil

*Shear strength of diffusion bonded joints.*

The properties of magnesium alloys allow them to be used in the various structural applications including biomedical applications such as implants. Given that that magnesium is non-toxic, biocompatible and biodegradable, these materials can be used to serve as implants or replacements of body tissues. The current use of titanium implants for bone treatment and implants in the tissues may be replaced by Mg alloys since titanium alloys are not biodegradable therefore another operation/surgery is needed in most cases after the healing of the affected tissues. One direction is to develop new Mg alloys with various alloying elements such as Zn, Al, Zr, and others, in order to reach the desired degradation rate suitable for the human body. Another challenge in using Mg alloy for bone fixation is the low mechanical strength of Mg when compared to Ti.

A significant challenge, however, is identifying suitable joining technologies capable of welding/joining magnesium to other metals such as Ti and prevents IMC formations. While conventional fusion welding is also capable of a selective dissimilar joining of Mg alloys the product of these processes is not suitable for biomedical applications. On the other hand, soli-state diffusion bonding, TLP diffusion bonding process and friction stir welding have demonstrated greatest potential for the dissimilar joining of Mg alloys.
