MICROSTRUCTURE OF HIGH-PERFORMANCE PURE AL/NANO-SI3 F. He and E. Forthofer
Copyright © 2011 American Foundry Society In this research, Si3
poured into a metal mold to cast the specimens. The micro- structure of the specimens was observed with a SEM.
N4
Ultrasonic vibration was applied on the molten metal to dis- perse the individual nano particles from their agglomeration. The molten metal containing Si3
N4 nano particles was then
All the fracture surface images were taken on the fractured surface to avoid the contaminations of polishing product.
processed and dispersed into molten aluminum using ultra- sonic vibration aided casting method. Scanning Electron Mi- croscopy (SEM) has been used to observe the distribution of the particles in the solidified Al. The SEM images show that most of the nano particles are distributed uniformly in the Al, while small clusters are still observed. The particles proved to be able to strengthen the pure Al while not affecting the thermal and electrical conductivity. The strengthening mechanism was also analyzed and proved by the SEM im- age. Al matrix composite have been widely used in industry, because of the higher tensile strength compared to pure Al. However, the ductility of Al will decrease with the addition of micro size ceramic particles. Metal Matrix Nanocompos- ite (MMNC), using nano size ceramic particles to strengthen the metal, has proven to be able to greatly reinforce light metals (Al, Mg) while not affecting the ductility of the pure metal. Casting is one of the most cost-effective ways to pro- duce metal matrix nanocomposite. Pure Al (99.99%) was melted and held at 750C in a graphite crucible. 0.5 wt.% of 30nm sized Si3
N4 particles was added into molten metal. of nano size have been successfully
The fractured surfaces of the tensile testing samples were observed and show the ductile fracture characteristic.
The particles could be observed on the fractured surface in Fig 2. The distribution of Si3
Also, at the fractured surface, the interaction between the metal and the ceramic particles can be observed, as shown in Fig 3.
N4
improved mechanical properties compared to pure Al. Al/2.0 Si3
The tensile testing was conducted at 100C. Al/0.5 Si3 N4
N4 p shows highest UTS and 0.2% offset yield strength. p has particles is uniform in the matrix.
N4
COMPOSITES Mechanical Engineering Technology, Purdue University, West Lafayette, IN, USA
Figure 2. Si3N4 nanoparticles can be observed on the fractured surface of Al/ Si3
N4 p with high magnification.
Figure 1. Fracture surface of Al/2.0Si3
N4
p. International Journal of Metalcasting/Winter 11
Figure 3. Particles found in the trenches observed on the fractured surface of Al/ Si3
N4 composites. 71
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87