Research Article
Effect of Solidification Rate and Rare Earth Metal Addition on the Microstructural Characteristics and Porosity Formation in A356 Alloy
| (a) Silicon particle characteristics of La-containing A356 alloy samples obtained from step-like mold castings |
| | Alloy code | Mold temp. (°C) | Mold section | RE addition | Silicon particle characteristics | | Actual | Area (µm2) | Length (µm) | Aspect ratio | Density (number/mm2) | | La (wt.%) | Average | SD | Average | SD |
| | 12S | 200 | Small (SDAS: 16 µm) | 0 | 3.663 | 5.680 | 3.444 | 3.567 | 2.272 | 13495 | | 22S | 0.165 | 1.685 | 3.740 | 2.132 | 2.376 | 2.044 | 27050 | | 32S | 0.356 | 1.364 | 3.825 | 1.898 | 2.229 | 2.029 | 38893 | | 42S | 0.685 | 1.464 | 3.665 | 1.952 | 2.119 | 2.022 | 33243 | | 52S | 1.025 | 1.506 | 4.175 | 1.879 | 2.306 | 1.978 | 35101 |
| | 12L | 200 | Large (SDAS: 31 µm) | 0 | 7.876 | 12.290 | 5.591 | 5.970 | 2.548 | 6471 | | 22L | 0.165 | 6.763 | 11.410 | 4.743 | 5.394 | 2.230 | 7416 | | 32L | 0.356 | 5.334 | 7.426 | 4.475 | 3.772 | 2.107 | 11179 | | 42L | 0.685 | 5.194 | 10.910 | 4.318 | 4.639 | 2.162 | 6644 | | 52L | 1.025 | 2.727 | 6.007 | 2.678 | 2.962 | 2.129 | 11145 |
| | 14S | 400 | Small (SDAS: 22 µm) | 0 | 5.245 | 7.768 | 4.360 | 4.452 | 2.393 | 9361 | | 24S | 0.165 | 3.371 | 4.856 | 3.148 | 2.908 | 2.147 | 13055 | | 34S | 0.356 | 5.152 | 8.234 | 4.119 | 4.040 | 2.129 | 10819 | | 44S | 0.685 | 4.517 | 7.080 | 3.671 | 3.844 | 2.092 | 13439 | | 54S | 1.025 | 2.680 | 5.351 | 2.648 | 3.153 | 2.034 | 25475 |
| | 14L | 400 | Large (SDAS: 41 µm) | 0 | 15.800 | 24.850 | 8.113 | 9.591 | 2.565 | 3457 | | 24L | 0.165 | 13.830 | 21.330 | 7.083 | 8.016 | 2.463 | 4007 | | 34L | 0.356 | 15.160 | 24.430 | 7.668 | 9.044 | 2.385 | 3555 | | 44L | 0.685 | 14.240 | 23.500 | 7.072 | 8.191 | 2.411 | 3788 | | 54L | 1.025 | 9.514 | 16.030 | 5.746 | 6.027 | 2.363 | 5904 |
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Note. Small: sample sectioned from step of 5 mm height. Large: sample sectioned from step of 20 mm height. SD: standard deviation.
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| (b) Silicon particle characteristics of La-containing Sr-modified A356 alloy samples obtained from step-like mold castings |
| | Alloy code | Mold temp. (°C) | Mold section | Composition | Silicon particle characteristics | | Actual | Area (µm2) | Length (µm) | Aspect ratio | Density (number/mm2) | | Sr (ppm) | La (wt.%) | Average | SD | Average | SD |
| | S12S | 200 | Small | 83.3 | 0 | 0.875 | 3.592 | 1.268 | 1.212 | 1.84 | 85236 | | S22S | 95.0 | 0.165 | 0.860 | 4.796 | 1.235 | 1.964 | 1.92 | 57253 | | S32S | 84.1 | 0.356 | 0.669 | 3.963 | 1.108 | 1.330 | 1.81 | 90306 | | S42S | 105.8 | 0.685 | 0.689 | 3.756 | 1.205 | 1.473 | 1.84 | 79410 | | S52S | 108.3 | 1.025 | 0.853 | 4.438 | 1.246 | 1.685 | 1.85 | 74495 |
| | S12L | 200 | Large | 83.3 | 0 | 1.653 | 3.738 | 1.948 | 1.661 | 1.89 | 48426 | | S22L | 95.0 | 0.165 | 1.606 | 4.175 | 1.897 | 1.976 | 1.96 | 33046 | | S32L | 84.1 | 0.356 | 1.401 | 3.898 | 1.763 | 1.820 | 1.95 | 39323 | | S42L | 105.8 | 0.685 | 1.364 | 4.134 | 1.766 | 2.043 | 1.95 | 46551 | | S52L | 108.3 | 1.025 | 1.406 | 4.180 | 1.853 | 2.229 | 2.02 | 37318 |
| | S14S | 400 | Small | 79.1 | 0 | 0.996 | 3.526 | 1.548 | 1.465 | 1.83 | 74841 | | S24S | 73.1 | 0.165 | 1.020 | 3.681 | 1.389 | 1.431 | 1.81 | 65911 | | S34S | 77.0 | 0.356 | 0.899 | 3.619 | 1.409 | 1.485 | 1.88 | 75695 | | S44S | 88.0 | 0.685 | 0.768 | 3.504 | 1.288 | 1.282 | 1.90 | 58987 | | S54S | 89.5 | 1.025 | 1.042 | 5.243 | 1.539 | 2.948 | 1.91 | 65816 |
| | S14L | 400 | Large | 79.1 | 0 | 2.532 | 5.228 | 2.640 | 2.254 | 1.90 | 32512 | | S24L | 73.1 | 0.165 | 2.262 | 5.044 | 2.245 | 2.223 | 1.91 | 34871 | | S34L | 77.0 | 0.356 | 1.679 | 3.691 | 2.003 | 1.896 | 1.96 | 43197 | | S44L | 88.0 | 0.685 | 2.121 | 5.302 | 2.287 | 2.652 | 1.99 | 35591 | | S54L | 89.5 | 1.025 | 2.471 | 3.718 | 2.600 | 1.748 | 2.06 | 30309 |
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Note. Small: sample sectioned from step of 5 mm height. Large: sample sectioned from step of 20 mm height. SD: standard deviation.
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