【摘要】 测量Ｆｅ２８Ａｌ和Ｆｅ４０Ａｌ合金的正电子寿命谱参数，计算合金基体和缺陷处的价电子密度。Ｆｅ２８Ａｌ和Ｆｅ４０Ａｌ合金基体的价电子密度（ｎｂ）分别为４１０×１０－２ａｕ和２３６×１０－２ａｕ，表明当Ａｌ和Ｆｅ结合形成Ｆｅ２８Ａｌ或Ｆｅ４０Ａｌ合金时，Ａｌ原子提供价电子与Ｆｅ原子的３ｄ电子形成局域的共价键，Ｆｅ２８Ａｌ和Ｆｅ４０Ａｌ合金中金属键和共价键共存。两种合金均有开空间大的缺陷，晶界缺陷处价电子密度（ｎｄ）〔１３２×１０－３ａｕ（Ｆｅ２８Ａｌ），４７０×１０－３ａｕ（Ｆｅ４０Ａｌ）〕比基体的低，表明晶界处的键合力较弱。Ｆｅ４０Ａｌ合金晶界缺陷的开空间比Ｆｅ２８Ａｌ的大。更多还原

【Abstract】 Positron lifetime measurements have been performed in binary Fe 28Al and Fe 40Al alloys. The valence electron densities of bulk and microdefects in all tested samples have been calculated by using the positron lifetime parameters. The densities of valence electron in the bulks of Fe 28Al and Fe 40Al alloys are 4 10×10 -2 a u , 2 36×10 -2 a u respectively. It indicates that, in Fe atom the 3d electrons have well localized properties and tend to form covalent bonds with Al atoms. The bonding nature in Fe 28Al or Fe 40Al is a mixture of metallic and covalent. The large open volume defects occur on grain boundaries in Fe 28Al and Fe 40Al alloys. The bonding cohesion of the grain boundaries in the tested samples is weak due to the low density (n d) 13 2×10 -3 a u (Fe 28Al),4 70×10 -3 a u (Fe 40Al) of valence electron there. The open volume of defects on the grain boudary in Fe 40Al alloy is larger than that in Fe 28Al alloy.更多还原