The in-situ Ti alloying of aluminum alloys and its application in A356 alloys

This research has investigated the in-situ Ti alloying of aluminum alloys and its application to A356 alloys and wheels through the evaluation of microstructure and mechanical properties. The results showed that stable titanium content can be obtained by adding a small quantity of TiO2 into electrolyte of pure aluminum. Under this approach, a greater than 95% absorptivity of titanium was achieved, and the microstructure of the specimens was changed to fine equiaxed grains from coarse columnar grains in the pure aluminum. In comparison with the tradition A356 alloys and wheels, the corresponding microstructure in the testing A356 alloys and wheels was finer. Although the tensile strength was similar between the testing and the tradition A356 alloys and wheels, the ductility of the former (testing) is superior to that of the later (tradition), leading to an excellent combination of strength and ductility from the testing alloys and wheels.

介电弹性体材料的新理解及其在全柔性人工心脏的应用

介电弹性体材料是指在电场下可以发生形变的弹性体材料,通常认为,介电弹性体在电场下的电致形变是由麦克斯韦应力挤压造成的,是力引发的应变.然而按照这一理论,不同介电弹性材料的理论形变和实际形变差别很大,毫无相关性.本文提出了一个用于解释其电致形变的新模型.该模型认为介电弹性体的电致形变是电场直接引发的:首先高分子链上的偶极在电场下被取向,而后拖拽高分子主链运动,造成构像的变化,最终产生电致形变.依据这一模型,可以很好地解释以往理论无法解释的问题.而后基于这一模型,设计合成了一种聚膦腈介电弹性体材料.该材料在不做预拉伸的情况下,可以达到80%的电致形变,具有目前最好的综合性能.最后基于该聚膦腈材料,设计制备了一种新型的全柔性人工心脏模型,其具有和人体心脏完全相同的工作特性,有望用于制备全柔性人工心脏.