| Summary: | 碩士 === 國立交通大學 === 材料科學與工程系所 === 95 === In this research, an A356-20%SiC composite through different equal channel angular extrusion (ECAE) conditions of mold type、extrusion speed and extrusion temperature were investigated. Microstructure and properties of the A356-20%SiC composite through different extrusion temperatures were studied.
The A356-20%SiC composite through 120°channel angle without additional angle Ψ extrusion had less breakage. The A356-20%SiC composite through 120°channel angle with additional angle Ψ extrusion generated ladder shape breakage with changing extrusion speed and extrusion temperatures under 100℃. However, the A356-20%SiC composite of 200℃ and 300℃ extrusion did not generated ladder shape breakage. Hardness of specimens through 25℃ to 75℃ extrusion resembled to hardness of the raw material which was HV 88. When extrusion temperature increased to 300℃, hardness was decreased to HV 84. SiC particles were accumulated at specimen surface and region of inner point of intersection of the two channels； however, that of 200℃ and 300℃ extrusion specimen was distributed more uniformly. The porosity fraction at 25℃ extrusion temperature is 7.5%, which was decreased to 4% at 300℃ extrusion temperature. No prefer orientation was produced by observing porosity fraction of different planes.
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