形狀記憶複合材料(TiNif/A356)的製備及其機械性質之研究

Abstract

本研究係以擠壓鑄造法製作鈦鎳形狀記憶纖維強化鋁合金(A356)之複合材料。在擠壓鑄造後，複材有無施予形狀記憶熱處理及所施行的熱處理條件不同，將會影響形狀記憶複材的機械性質。 TiNi纖維及形狀記憶複合材料的麻田散體相變化溫度皆經由熱差掃瞄儀(DSC)的量測而獲得。從DSC的結果得知，TiNi纖維的麻田散體相變化溫度在被壓鑄於鋁合金基材內後會因此而提高。由pin-on-disk 的磨耗測試結果顯示，含10vol%TiNi形狀記憶複材比未含有TiNi纖維強化的鋁合金具有優越的抗磨耗性。且經過形狀記憶熱處理的複材擁有更佳的抗磨耗性，大約比未受形狀記憶熱處理的複材減少20%的磨耗重量損失。含6.7vol% 的TiNi形狀記憶複材的拉伸性質試驗是在Ａf(沃斯田體相的完成溫度)溫度之上(60℃)進行。經過形狀記憶熱處理的複材所具有的拉伸強度和所施予預應變值的大小成正比。由TiNi纖維的形狀記憶效應所引起的體積收縮會導致鋁基材內產生殘留壓應力，因此幫助複材在受到4.5%預應變之後可獲得約16%(30MPa) 的拉伸應力提昇。而且研究結果也發現，經過500℃，30分鐘形狀記憶熱處理的複材比在500℃，300分鐘形狀記憶熱處理的複材具有較佳的拉伸性質。

In this study, TiNi shape memory alloy (SMA) fiber-reinforced Al (A356) matrix composites were fabricated by squeeze casting. Different shape heat treatment conditions of TiNi/Al composites influenced their mechanical behavior. The martensitic transformation temperatures of TiNi fibers and composites were measured by the differential scanning calorimeter method (DSC). The DSC results indicated the martensitic transformation temperatures of composites increased after TiNi fibers embedding into the Al matrix. The wear tests were carried out on a pin-on-disk machine. The wear results showed that composites with 10vol%TiNi exhibited higher wear resistance than their monolithic alloys and the composite with heat treatment also had the lower 20% wear loss compared to the one without heat treatment. The tensile tests of the composites with 6.7vol%TiNi were carried out at 60℃ above Af (austenite finish temperature) which was found from the DSC analysis. The tensile strength of composites after heat treatment increased with increasing the prestrain. Due to the compressive stress in the Al matrix caused by shape memory shrinkage of TiNi fibers, the tensile strength of composites increased 16%(30MPa) after 4.5% prestrain. It was also found that the composite with heat treatment at 500℃ for 30 minutes had a better tensile performance than the one with 500℃ for 300 minutes shape heat treatment.