Anticipating Chinese aeronautlcal industry's need in the not too distant future for SiCParticulate reinforced Al-Li alloy
matrix composites, we study the improve ment of thestrength-ductility combination and present our research results in this research summary.The undesirable feature of existing
SiC particulate reinforced Al-Li mains composite isthat its ductility is too low<3>. Our five-year experience with
Al-Li+Ce Alloy leads us tobelieve that changing the matrix from Al-Li to Al-Li+Ce may improve the ductility of thecomposites) because ductility of Al-Li+Ce is much better than that of Al-Li. We believewe are the first to try SIC particulate reinforced Al-Li+Ce matrix composites as far as openliterature is concerned. The tension test results of Al-Li alloy, Al-Li+Ce alloy and SiCparticulate reinforced Al-Li+Ce alloy matrix composites are given in top, middle and bottom rows respectively in Table 2. In Table2, 4 is the ultimate strength, σ0.2 is the 0. 2% offset yield strength, and 5 is the percentage elongation. It can be seen that 6 in the middle row(7. 33%)is 24. 2% higher than that of top row (5. 90%),and 6 in the bottom row (7. 20%)isonly a litile lower than that of middle row, thus indicating that changing matrix to Al-Li+Ce gives satisfactory result as expected.We are of the opinion that adding cerium improves the ductility of composites , i. e.,itsstrength-ductility combination, because such addition improves the moisture permeabilitybetween the matrix and SiC particulate.The chemical composition (weight percent)is listed in Table 1.