High Temperature Strength of Al-Fe-(Cr, Mn, V)-Ti Alloys with Dispersed Quasi-Crystalline Particles Solidified by Powder Metallurgy

点击翻译按钮获取中文摘要

Abstract of contents: Alloy design policies of Al-base alloys with high temperature strength was as follows: 1) Atomic sizes of composition elements should be widely different, 2) Alloys should be multi-components, 3) Heat of mixing among main component elements should be negative and 4) Added elements should have lower diffusion coefficient. As a result, we found that a liquid quenched Al-Fe-Cr-Ti-Co-Mo alloy system have a certain composition range where the fine particles of quasi-crystals are dispersed in fcc-Al phase.Rapidly quenched alloy powder of the above composition (content of Al was 93-95 at%) was solidified by PM under conditions of extrusion temperature = 673 K and extrusion ratio = 11. The high temperature strength of thus prepared PM alloy was excellent showing the tensile strength (σuts) of >300 MPa and >150 MPa at 573 K and 673 K, respectively. Transmission electron microscopy (TEM) showed that quasi-crystallites of about 100 nm in size with high temperature stability and high hardness were dispersed in the fcc Al-phase. The high temperature strength was attributed to the structure observed by TEM. Especially, ours of Al_<93>Fe_<2.45>Cr_<2.45>Ti_<0.8>Co_<0.8>Mo_<0.5> alloy was very high, that is, 364 MPa and 203 MPa at 573 K and 673 K, respectively.Significance= The target figure of the high temperature strengh of Al-alloy was >300 MPa at 573 K. The high temperature strengh of Al_<93>Fe_<2.45>Cr_<2.45>Ti_<0.8>Co_<0.8>Mo_<0.5> alloy PM material developed by present research is much higher the figure, and therefore, we attained the purpose.Importance: This developed Al-alloys having light-weight and high temperature strength can be used for the high temperature part of the transportation machines to seek the fuel cost improvement. And therefore, this developed Al-alloys are very important materials as one of candidate for the environmental problems solution.