Al-Si系粉末合金の超塑性

Superplasticity of Al-Si P/M Alloys Satoru Ishihara, Mikio Kondoh, Kazuhiko Itoh Al-17Si-4.5Cu-0.5Mg-(06)Fe-(02)Mm ( Mm : ) (i) (ii) Si(iii) Fe (iv) Mm Al-17Si-4.5Cu-0.5Mg500 10 2 s 1 520 110 1 s 1 Si Fe 10 0 s 1 Al-Si Al-17Si-4.5Cu-0.5Mg-(06)Fe-(02)Mm (Mm : misch metal) rapidly solidified powder metallurgy (RSP) alloys were prepared by the hot extrusion method. Effects of the testing temperature, the Si particle size, the Fe content and the misch-metal addition on the high temperature tensile property and deformation behavior of these alloys were investigated. In Al-17Si-4.5Cu- 0.5Mg alloys, the superplastic behavior was observed at 500 with an initial strain rate of 10 2 s 1. At 520, superplasticity was obtained at an initial strain rate 10 1 s 1 which is higher than the case at 500. The tensile elongation by superplasticity increased with decreasing Si particle size, but superplasticity was obtained at the same strain rate. With increasing Fe content, the average matrix grain size decreased and the superplastic strain rate increased, but the maximum tensile elongation decreased. The misch-metal addition has a significant effect of retardation coarsening of matrix grains by homogeneous precipitation particles, and superplasticity was obtained at a high strain rate of 10 0 s 1. It is concluded that the superplastic elongation of Al-Si RSP alloys is affected by the size of dispersing particulates. Al-Si

Al-Si 10 4 10 2 s 1 10 2 10 2 s 1 Al-Si SiAl-Si Si Al-Si Al-Si Si Al-Si Alloy A B C D Si Al-Si Fe3 Al-Si (i) (ii) Si (iii) Fe(iv) Mm Al-17Si-4.5Cu-0.5Mg mass% 2%4%6%Fe2%Mm FeMm2% 6Fe 2Fe-2Mm 44µ m 450 12.7 400 Si 4 A Atomized powder 44µm 44145µm Preparation condition Hot extrusion Hot extrusion Heat treatment 753K, 3.6ks Heat treatment 753K, 173ks Hot swaging Hot swaging Hot swaging Hot swaging Preparation conditions of Al-17Si-4.5Cu-0.5Mg P/M alloys.

0.2% X 50µm Si Si Si TEM 1.74 5mmφ4mm 900s 50010 2 s 1 520500 110 1 s 1 540 0.1 σε σ =Kε m 1 Kmm m1 m=dlogσ dlogε 2 Fig. 5 m 0.21 400 0.28 450 0.48 500 Si -a) 400500 Optical micrograph of Al-17Si-4.5Cu-0.5Mg P/M alloy ( alloy A ).

Elongation ( % ) Flow stress, σ 0.1 / MPa TEM micrographs of P/M alloys, a) Al-17Si-4.5Cu-0.5Mg, b) Al-17Si-4.5Cu-0.5Mg-2Fe, c) Al-17Si- 4.5Cu-0.5Mg-4Fe, d) Al-17Si-4.5Cu-0.5Mg-6Fe, e) Al-17Si-4.5Cu-0.5Mg-2Mm, f) Al-17Si-4.5Cu-0.5Mg- 2Fe-2Mm. 400 300 500 520 10 2 1 10 450 400 200 450 10 0 500 520 100 400-1 10 540 0 10-4 540 10-3 10-2 10 0 Initial strain rate, ε 0 / s 1 10 1 10-2 10 0 10-3 10-2 Initial strain rate, ε 0 / s 1 Effect of the testing temperature on elongation as a function of the intial strain rate for Al- 17Si-4.5Cu-0.5Mg P/M alloy. Effect of the testing temperature on flow stress as a function of the initial strain rate for Al- 17Si-4.5Cu-0.5Mg P/M alloy.

0.48 520 400500 m 0.3<m1.0 500 520 500520 520 Fig. 6-b 500 Fig. 6-a 0.2µm Fig. 6-c EDX Si5 Cu4.5Mg 0.5%Si Si520 Si 5mm 500 10 2 s 1 Fig. 7 SEM fractgraphs of Al-17Si-4.5Cu-0.5Mg P/M alloy after tensile tests at a) 500 TEM micrograph of alloy A, after tensile test at 500 and at initial strain rate of 10 2 s 1 ( a : elongated grain, b : Si particle, c : smaller grain ).

52010 1 s 1 Fig. 8 EDX TEM micrograph of alloy A, after tensile test at 520 and at initial strain rate of 10 2 s 1. Si Si Higashi Fig. 8 4 Si A µm µm 3.4µm D 4.7µm Optical micrographs of Al-17Si-4.5Cu-0.5Mg P/M alloy prepared under various condituions as Fig. 1. a) Alloy A, b) Alloy B, c) Alloy C, d) Alloy D.

Elongation Elongation ( % ) ASiB AB CD SiB 480Si SiAD 3.3µm A 3.5µm D Si 4 500 Si 10 2 s 1 4 Si 10 2 s 1 Si ABCD Si Si3.3µm 3.3µm AD10 2 s 1 SiA SiD Si Si Si 400 Al-17Si-4.5Cu-0.5Mg T = 773K 300 400 Alloy A Al-17Si-4.5Cu-0.5Mg 200 Alloy B 100 0 10-4 Alloy A B C D 10-3 d Si 2.3µm 2.9µm 3.4µm 4.7µm 10-2 10 0 Initial strain rate, ε 0 / s 1 10 1 Elongations at 773K as a function of initial strain rate for Al-17Si-4.5Cu-0.5Mg P/M alloys with different Si particle sizes. 300 200 T = 773K ε= 1 10 2 s 1 Alloy C Alloy D 2 3 4 5 Si perticle diameter / µm Plots of elongation against Si particle size for Al-17Si-4.5Cu-0.5Mg P/M alloys.

10 2 s 1 5mm A Fig. 7 SiD Fig. 13 Fig. 13-a) Fig. 13-b) Fig. 13-c) Si Si 500520 Al Fig.713 SEM micrographs of Al-17Si-4.5Cu-0.5Mg P/M alloys, a) alloy A and b) alloy D, after tensile test at 773K and at initial strain rate of 10 2 s 1. TEM micrographs of alloy D, after tensile test at 773K and at initial strain rate of 10 2 s 1.

Elongation ( % ) Flow stress, σ 0.1 / MPa AD DFig. 13-a) Si X Fe Fe SiFe Si Fe Fe Fig. 3-a), b), c)d) Fe Si Fe Fe 500 Fe 10 2 s 1 Fe 6Fe10 0 s 1 Fe Fem m 0.5 Fe 3 400 300 Al-17Si-4.5Cu-0.5Mg-xFe 0Fe (Alloy A) 0Fe 2Fe 4Fe 6Fe 1 10 10 0 Phases of Al-17Si-4.5Cu-0.5Mg-xFe-yMm. 200 2Fe 6Fe 0 Fe 2 Fe 4 Fe 6 Fe 100 4Fe 0 Mm 2Mm Al Si Al2Cu Al Si Al2Cu Al2(Si,Cu)2RE RE Lanthanoid Al Si Al7Cu2Fe Al5FeSi Al Si Al7Cu2Fe Al5FeSi Al2(Si,Cu)2RE Al Si Al7Cu2Fe Al5FeSi Al Si Al7Cu2Fe Al5FeSi 0 10-3 10-2 10 0 10 1 Initial strain rate, ε 0 / s 1 Effect of the Fe content on elongations and flow stresses as a function of initial strain rate for Al-17Si-4.5Cu-0.5Mg-xFe P/M aloys.

Al-Si Al Fe Fe Fe Si Fe4Fe Si Si Fe Optimum superplastic strain rate / s 1 10 0 10-2 0Fe 2Fe 4Fe 6Fe 2.9 Al-17Si-4.5Cu-0.5Mg-xFe 10 0 Inverse grain size / µm 1 10 1 Plots of optimum superplastic strain rate against inverse grain size of P/M alloys with different Fe content. X Table 1 Al 2 (Si, Cu) 2 RE RE Fe Si 2Mm 2Fe-2MmFig. 3-e)f)Mm 2Fe Fig. 3-b) Mm 2Fe 2Fe FeAl 2 (Si, Cu) 2 RE 500 Mm 2Mm2Mm- 2Fe2Fe10 0 s 1 2Mm2Fe FeMm 2 1 MmFe 2Mm-2Fe 2Mm m 0.5 m10 0 s 1 10 1 s 1 2Fe

Elongation ( % ) Flow stress, σ 0.1 / MPa Al-SiSi Si m0.5 Si SiFeMm Fig. 17 Si Mm 400 300 Al-17Si-4.5Cu-0.5Mg-xFe-yMm Alloy A Alloy A 2Fe 2Mm 2Mm-2Fe 2Mm 1 10 10 0 Al-Si 1 2 3 4 5 6 RD -21995, 13 (1988), 489 (1988), 492 PM (1992)54 PM(1992) 42, 1980 7 RD-11990, 54 8 ( ), (1994), 312 0.1µm 1µm 10µm 200 2Fe Particulate size Compound with Mm Compound with Fe 100 0 10 10 0 1 Initial strain rate, ε 0 / s 1 10-3 10-2 2Mm-2Fe Retardation coarsening of matrix grain Affection of grain boundary sliding Elongation Effective Harmless Large Si particle Uneffective Harmful Small Effect of the Mm addition on elongations and flow stresses as a function of initial strain rate for Al-17Si-4.5Cu-0.5Mg-xFe P/M alloys. Relations between particulate size and superplastic property.

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