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Reinforcement of light-weight metal alloys using nanomaterials

Technology Number: 

1783

Patent Status: 

Pending
Summary 

Aluminum and magnesium alloys are gaining more recognition for light-weight materials applications. In spite of this, such alloys have not been used for critical mechanical applications mainly due to their inferior mechanical properties compared to other engineering materials such as steel. Hence, many researchers have attempted to reinforce these alloys and obtain light-weight materials with excellent mechanical properties. The reinforcement process of the alloy can be achieved by introducing another material to form metal matrix composites. Different studies show that such composites exhibit improved properties, such as increased yield strength and tensile strength, enhanced stiffness, improved thermochemical properties, etc. However, the introduction of nanomaterials into the metal matrix is rather difficult due to the harsh manufacturing conditions employed for processing the metal composites.

The group of Prof. Reshef Tenne has developed state-of-the-art aluminum- and magnesium-based metal matrix composites, comprising small amounts of inorganic nanomaterials, such as nanotubes and spherical nanoparticles. The new nanocomposites exhibit much superior mechanical properties compared to the pristine alloy.

 

Table 1: Mechanical properties of different alloys reinforced with nanoparticles versus their neat form

Metal

Alloy

Neat UTS, MPa

Neat elongation

Added Nanoparticles

improvement UTS, %

improvement elongation, %

Aluminum

AA6061

170

0.28

0.2wt.% INT

21%

68%

AA6061

170

0.28

0.2wt.% IF

16%

39%

AA356

175

0.09

0.02wt.% INT

9%

44%

Magnesium

AZ31

135

0.14

0.2wt.% INT

54%

85%

AZ61

130

0.10

0.2wt.% INT

45%

96%

Applications


·         Automotive, transportation, and aerospace industries

·         Jet engine technologies

·         Electronics

·         Medical technologies


Advantages


·         Light-weight metal alloys

·         Excellent mechanical properties

·         Straight-forward fabrication technique


Technology's Essence


Aluminum and magnesium alloys were combined with small amounts (up to 0.5 wt.%) of either tungsten disulfide nanotubes (WS2 INT) or inorganic fullerene-like tungsten disulfide nanoparticles (WS2 IF) to form metal matrix composites (MMC) using a melt-stirring reactor operated at high temperatures (Al MMCs: 250-750?C; Mg MMCs: 400-720?C). These nano-structures exhibit unique mechanical properties, which make their usage as a metal reinforcement very promising. The nanoparticles showed quite a remarkable stability at these elevated processing temperatures and were found to be uniformly distributed. Despite the small amounts of added nanostructures, their addition led to remarkable improvements in the mechanical properties of the alloys. Surprisingly, both the tensile strength of the alloys and their elongation were improved by approximately 10-50% and 40-100% (and consequently the fracture toughness was significantly increased), respectively. Depending on the nano-structure type and concentration, the hardness, yielding strength, ultimate tensile strength, and ductility were significantly improved. For example, the yielding strength, ultimate tensile strength (UTS), and ductility of AA6061/0.2wt.% WS2 INT MMCs were improved by 15%, 21% and 68%, respectively. Representative mechanical properties of different aluminum and magnesium alloys reinforced with nanoparticles versus their neat form are shown in Table 1. Stress-strain curves of AA6061 aluminum alloy reinforced with different nanoparticle loading are presented in Figure 1. Physical considerations suggest that the main mechanism responsible for the reinforcement effect lies in the mismatch between the thermal expansion coefficients of the metal and the nano-structures.

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