Effect of Trace Sc on (I) Mechanical Properties , (II) Thermal Stability, and (III) Quench Sensitivity Impact of Aerospace Al-7Si-0.6Mg Alloys(2/2)

A 3-year research proposal is planned as the topic: " Effect of trace Sc on (I) mechanical properties , (II) thermal stability, and (III) quench sensitivity impact of aerospace Al-7Si-0.6Mg alloys ”Al-7Si-0.6Mg alloy (ID:357 alloy ) is a heat-treatable Al-alloy with a good castability , weldability, high strength and abrasion resistance ,etc. It is very easy to mix the Fe, forming a Fe-rich intermediate compound with thick needle shape. The iron-rich phase is hard and brittle alloy that damage the mechanical properties (especially toughness). Add in Al-7Si-0.6Mg alloy with trace Be (0.05wt%) designated as A357 alloy is used as a missile material, can change the needle iron-rich phase to minor harmful spherical iron-rich phase. But Be is a highly toxic to cause the environmental safety problems.Missiles flying at high speed, resulting alloy friction and causing high surface temperature up to 190〇C. Traditional A357 alloys are often unable to match the high quality requirements of aerospace materials. In addition, A357 alloy with a high quench sensitivity problem, that is difficult to obtain a high aging strengthening effect, cause a decline in the overall component strength , resulting in parts requires heavy design.Due to environmental requirements and technological progress, aerospace Al alloys’ performance is asked more stringent, the development of lighter (i.e. the need for high strength - high quality Index, low quench sensitivity) and more heat-resistant (i.e. high thermal stability) of the alloy , is urgently in need of research and valuable .Our pre-study found that adding a small amount Sc (0.04wt%) to 357(Al-7Si-0.6Mg) alloy can enhance the quality index 17% , and can have the better at 250 C thermal stability and quench sensitivity decreased to50% . These preliminary findings are valuable, so planning for this 3-year research project, hope to develop an alloy with better properties compare to the current commercial aerospace A357alloy. Looking through the research, theoretical mechanisms can further explore these improvements. Hope the research results can as a useful reference to industry and academic .Research planning of each year as follows:1st year (In Progress): Trace Sc on (Al-7Si-0.6Mg) alloy to improve the mechanical properties. (enhance the quality indice 17% )2ndyear (Re-Application): Trace Sc on (Al-7Si-0.6Mg) alloy to improve the thermal stability. ( Goal : to enhance the thermal stability )3rd year (Re-Application): Trace Sc on (Al-7Si-0.6Mg) to improve the quench sensitivity. (Goal: low quench sensitivity )