Advances in Materials Science and Engineering

Research Article

Effect of Solidification Rate and Rare Earth Metal Addition on the Microstructural Characteristics and Porosity Formation in A356 Alloy

(a) Eutectic Si particle characteristics observed in variable angle mold (small) samples of A356 alloys containing La and Ce additions


Alloy code	RE content		Silicon particle characteristics
	Actual		Area (µm²)		Length (µm)		Aspect ratio	Density (number/mm²)
	La (wt.%)	Ce (wt.%)	Average	SD	Average	SD	Aspect ratio	Density (number/mm²)

DBS	0	0	5.990	7.032	5.957	7.421	2.671	8240
D10S	0.165	0	8.805	10.020	8.536	10.30	2.468	6037
D1S	0.356	0	6.492	6.958	6.459	11.70	2.282	8174
D2S	0.685	0	7.08	8.56	5.409	6.78	2.288	4201
D3S	1.025	0	3.211	5.164	3.101	5.82	2.221	10149
D11S	0.032	0.082	7.154	7.915	6.870	9.75	2.553	6307
D4S	0.136	0.185	6.413	7.472	6.307	8.53	2.533	7330
D5S	0.046	0.317	5.683	6.376	4.967	6.37	2.451	7902
D6S	0.089	1.088	8.105	9.673	6.094	9.01	2.367	6795
D7S	0.44	0.282	5.058	5.868	6.820	10.80	2.219	8331
D8S	0.781	0.877	5.917	6.754	7.555	9.96	2.355	6253
D9S	1.073	0.831	4.426	4.914	5.254	7.60	2.124	16277

Note. Mold temperature: 325°C; small: angle of variable angle mold is 0°.

(b) Eutectic Si particle characteristics observed in variable angle mold (large) samples of A356 alloys containing La and Ce additions


Alloy code	RE addition		Silicon particle characteristics
	Actual		Area (µm²)		Length (µm)		Aspect ratio	Density (number/mm²)
	La (wt.%)	Ce (wt.%)	Average	SD	Average	SD	Aspect ratio	Density (number/mm²)

DBL	0	0	21.45	29.53	9.467	9.397	2.586	35521
D10L	0.165	0	28.48	36.16	19.38	10.230	2.275	2349
D1L	0.356	0	18.24	28.87	11.42	9.498	2.237	5521
D2L	0.685	0	24.43	37.46	15.3	10.95	2.287	3754
D3L	1.025	0	19.59	13.96	9.374	5.804	2.195	9446
D11L	0.032	0.082	16.37	23.23	12.42	8.741	2.600	7352
D4L	0.136	0.185	16.19	25.41	10.23	8.960	2.499	5924
D5L	0.046	0.317	16.09	28.03	8.752	9.570	2.367	5668
D6L	0.089	1.088	18.66	31.05	9.310	10.410	2.305	5236
D7L	0.44	0.282	11.93	18.95	12.01	7.605	2.343	7515
D8L	0.781	0.877	15.95	24.51	13.200	8.162	2.332	4122
D9L	1.073	0.831	8.20	12.82	5.880	5.416	2.185	12862

Note. Mold temperature: 325°C; large: angle of variable angle mold is 15°.

(c) Characteristics of eutectic Si particles in variable angle mold (large) samples of Sr-modified A356 alloys containing La and Ce additions


Alloy code	Addition			Silicon particle characteristics
	Actual			Area (µm²)		Length (µm)		Aspect ratio	Density (number/mm²)
	Sr (ppm)	La (wt.%)	Ce (wt.%)	Average	SD	Average	SD	Aspect ratio	Density (number/mm²)

DBLS	127	0	0	1.765	3.906	2.161	2.431	2.061	64199
D10LS	69	0.165	0	2.138	3.930	2.345	2.378	1.952	58454
D1LS	109	0.356	0	2.385	5.157	2.494	2.958	1.974	42526
D2LS	74	0.685	0	4.240	2.470	2.625	8.348	2.370	5374
D3LS	74	1.025	0	5.775	2.633	3.815	4.688	2.262	18163
D11LS	73	0.033	0.082	3.549	6.440	3.207	3.862	2.114	38504
D4LS	70	0.136	0.185	1.876	3.542	2.165	2.053	1.937	55283
D5LS	71	0.046	0.317	2.524	4.593	2.565	2.854	1.906	49097
D6LS	77	0.089	1.088	1.885	4.197	2.155	2.435	1.927	61875
D7LS	75	0.44	0.282	3.119	5.461	2.931	3.235	1.927	36082
D8LS	78	0.781	0.877	7.421	12.000	4.937	5.439	2.184	17488
D9LS	72	1.073	0.831	4.622	7.183	3.840	4.001	2.151	26061

Note. Mold temperature: 325°C; large: angle of variable angle mold is 15°.