摘要
分析了挤压铸造制备ＣＦ／Ａ３５６复合材料的充填过程，研究了工艺参数对基体合金凝固组织的影响．实验结果表明，当预制件中纤维均匀分布时，存在三角形、正方形、六边形３种排列方式，其充填阻力Ｐ＝４．３２ＭＰａ．挤压铸造ＣＦ／Ａ３５６复合材料时，当浇注温度较高时，其凝固发生在整个浸渗过程结束之后，这是由于模具和纤维的激冷作用，而首先凝固的晶坯在浸渗过程中局部或完全重熔；基体合金初生α－Ａｌ相在纤维间隙中形核并逐渐向纤维表面长大；而共晶Ｓｉ相依附碳纤维表面形核并长大，当预制件预热温度高于基体熔点时，共晶Ｓｉ相包覆碳纤维表面长大．随着凝固冷却速率的降低，共晶Ｓｉ相形态发生从蠕虫状、细针状到片状或块状的转变，其尺寸由小到大变化．
In this paper, the authors have analysed the infiltration process of CF/A356 composites fabricated by squeeze casting and investigated the effect of technical parameters on the solidification microstructure of the matrix alloy. Experimental results showed that while carbon fiber (CF) arrangement in the perform was the uniform f there were three types of CF arrangement, i. e. staggered array, rectangular array and hexagonal array ; the resistance of infiltration of the preform was p = 4. 32MPa. During the process of CF/A356 composites fabricated by squeeze casting, when the pouring temperature was high, the solidification process would occur as an infiltration process fully performed. That is why the sharp cooling effects of the mould and CF caused the primary crystal nucleus to remelt partly or entirely. During the solidification process,α-Al phase of matrix alloy nucleated first in the interstice regions of CF, and grew gradually toward the surface of CF; but eutectic Si phase nucleated and grew on the surface of CF.When the preheating temperature of the pre form was higher than that of the melting point of the alloy, eutectic Si phase grew around the surface of CF. As the solidification cooling rate increased, the size of the eutectic Si phase also increased, and its shape was changed from a worm form and fine needle form to a slice form and block form.
出处
《上海交通大学学报》
EI
CAS
CSCD
北大核心
1996年第8期25-30,共6页
Journal of Shanghai Jiaotong University
基金
国家自然科学基金
国家教委博士点基金
