Aalloy组织相片.docVIP

Fig. 5. Effect of cooling rate on the solidification microstructure of Al–2.06 wt.% Si–1.58 wt.% Mg alloy. The corresponding cooling rates are: (a) 0.3 K/s; (b) 6.0 K/s;(c) 200 K/s. Fig. 1. Optial micrographs of the A356 cast alloys after solution heat treatment at 813 K for 8 h. (a) Permanent mold cast and un-HIPed, (b) permanent mold cast and HIPed, (c) semi-liquid die-cast. Highmagnification pictures in the windows show Si particle morphology. Fig.2 Optical microscopy under a polarized light for anodized specimens. (a) Pm, grain structure of HPm is the same as Pm (b) SS. Fig. 3. Fatigue crack initiation and successive meshy crack aggregation in HPm and SS. (a) An initiated crack at Si particle/matrix interface, (b) crack growth meshy morphology. Fig. 5. Scanning electron micrograph of water quenched sample,previously maintained at 560 _C during 480 s. Fig. 5. Fracture surface of A2 composite reinforced with 15% TiB2 in T1 precipitate state B Fig. 13. Scanning electron micrograph of a sample maintained at 580 _C during 600 s, showing liquid formation at E1 and melting of Si particles at E2. Liquid fraction in the former region is much higher than in the latter. Fig. 3. Microstructures of the rheo-cast A356 alloys after different ageing conditions (a) 0 h, (b) 2 h, (c) 4 h, (d) 8 h, (e) 10 h, (f) 16 h, (g) 24 h and (h) 72h at 150?C. Fig. 2. Micrographs of Al_/11.6%Si_/0.4%Mg alloys with partial modification, as-cast: (a) 0%Sr; (b) 0.015%Sr. Fig. 4. SEM micrograph of Al_/11.6%Si_/0.4%Mg with 0.010%Sr modification: (a) network structure; (b) bamboo-shoot shape structure. Fig. 5. SEM micrograph of the eutectic cell boundary zone in Al_/ 11.6%Si_/0.4%Mg alloys with 0.0375%Sr Sr modification: (a) low magnification; (b) high magnification