南华大学学报：自然科学版
南華大學學報：自然科學版
남화대학학보：자연과학판
Journal of University of South China(Science and Technology)
2011年
4期
85-90
,共6页
改进Miedema模型%纳米颗粒%钛基合金%形成焓%尺寸依赖性%成分聚集
改進Miedema模型%納米顆粒%鈦基閤金%形成焓%呎吋依賴性%成分聚集
개진Miedema모형%납미과립%태기합금%형성함%척촌의뢰성%성분취집
modified miedema model%nano particle%Ti based alloy%formation enthalpy%size-dependence%composition segregation
基于计算合金形成焓的改进Miedema模型和考虑纳米颗粒表面效应,研究了钛基二元纳米合金形成焓的尺寸和成分效应.计算结果表明钛基二元合金纳米颗粒的形成焓依赖颗粒尺寸,显示了明显的尺寸效应.纳米颗粒的形成焓随粒径的减小而增大,当粒径减小到某一临界尺寸时,纳米合金的形成焓由负值转变为正值,从而降低了纳米颗粒的热稳定性.当颗粒粒径小于10 nm时,纳米颗粒发生成分聚集,这种成分聚集发生的趋势取决于纳米合金的表面形成焓.
基于計算閤金形成焓的改進Miedema模型和攷慮納米顆粒錶麵效應,研究瞭鈦基二元納米閤金形成焓的呎吋和成分效應.計算結果錶明鈦基二元閤金納米顆粒的形成焓依賴顆粒呎吋,顯示瞭明顯的呎吋效應.納米顆粒的形成焓隨粒徑的減小而增大,噹粒徑減小到某一臨界呎吋時,納米閤金的形成焓由負值轉變為正值,從而降低瞭納米顆粒的熱穩定性.噹顆粒粒徑小于10 nm時,納米顆粒髮生成分聚集,這種成分聚集髮生的趨勢取決于納米閤金的錶麵形成焓.
기우계산합금형성함적개진Miedema모형화고필납미과립표면효응,연구료태기이원납미합금형성함적척촌화성분효응.계산결과표명태기이원합금납미과립적형성함의뢰과립척촌,현시료명현적척촌효응.납미과립적형성함수립경적감소이증대,당립경감소도모일림계척촌시,납미합금적형성함유부치전변위정치,종이강저료납미과립적열은정성.당과립립경소우10 nm시,납미과립발생성분취집,저충성분취집발생적추세취결우납미합금적표면형성함.
The effects of grain size and composition on the formation enthalpy of nano binary Ti-based alloy are investigated by taking the surface effect into account within the modified Miedema model.It is demonstrated that the formation enthalpy of binary Ti based alloy with nano grains is size-dependent and exhibits evident size-effects.The formation enthalpy increases with the size decrease,and its value turns from negative to positive at a critical size,which will weaken the thermal stability of the nano grains.Furthermore,the composition segregation taking place in the nano grains of the Ti based alloy is obvious when the grain size is less than 10 nm and the tendency of segregation is dependent on the surface formation enthalpy of nanoparticle.
