Al-Fe-Ce合金熔体结构及主要强化相形成的EET分析

Melt Structure and Formation of Main Strengthening Phases in Al-Fe-Ce Alloy with EET Theory

在较慢冷却条件下,Al-Fe合金熔体中面心立方结构的近程有序原子集团占主导地位。基于EET(empirical electron theory of solids and molecules)理论,计算了Al-Fe-Ce合金熔体中fcc结构近程有序原子集团Al-Fe,Al-Ce,Al-Fe-Ce,α-Al和主要析出相Al3Fe,Al6Fe,Al8Fe4Ce和Al4Ce的价电子结构,分析了Ce对Al-Fe合金熔体和主要强化相形成的影响。研究发现:Al-Fe最强键的n1α-Al--Fe(n1为共价电子对数)比α-Al的n1α-Al大14.2%,Al-Fe近程有序原子集团为二元AlFe相的形成提供了形核条件。Al-Ce,Al-Fe-Ce最强键的n1α-Al-Ce,n1α-Al-Fe-Ce分别比AlFe的n1α-Al-Fe大38.2%,39.3%,Ce添加促进了Al-Ce,Al-Fe-Ce原子集团的形成,减少了Al-Fe原子集团,为AlCe,AlFeCe相的形成提供了形核条件。对于Al-Fe合金,由于FAl6Fe(F为结构单元总成键能力)小于FAl3Fe,所以Al6Fe相优先形成。对于Al-Fe-Ce合金,由于FAl8Fe4Ce<FAl4Ce<FAl6Fe,所以优先形成的细小短棒状Al8Fe4Ce相可消耗Fe原子,进而减少了粗大针状、团球状Al3Fe,Al6Fe相的形成。Al8Fe4Ce最强键的n1Al8Fe4Ce与Al3Fe最强键的n1Al3Fe相近,Al4Ce最强键的n1Al4Ce与Al6Fe最强键的n1Al6Fe相近。Al4Ce强弱键键合力差距较大,Al8Fe4Ce键络分布较均匀,不存薄弱键合环节。

Under slower cooling conditions,the short range ordered atomic groups with face-centered cubic structure in Al-Fe alloy melt were dominant.Based on the empirical electron theory(EET)of solids and molecules,the valence electron structures of the FCC type short range ordered atomic groups Al-Fe,Al-Ce,Al-Fe-Ce,α-Al and the main precipitates Al3 Fe,Al6 Fe,Al8 Fe4 Ce,Al4 Ce in Al-Fe-Ce alloy were calculated,furthermore,the effects of Ce on melt structure and formation of main strengthening phases of Al-Fe alloy were analyzed.The covalent electron pairs n1α-Al-Feof the strongest bond of Al-Fe was 14.2%larger than that ofα-Al,the short range ordered atomic group of Al-Fe provided nucleation conditions for the formation of binary AlFe phase.The n1α-Al-Ceand n1α-Al-Fe-Cevalues of the strongest bond of Al-Ce and Al-Fe-Ce were 38.2%and 39.3%higher than that of Al-Fe,respectively,Ce addition promoted the formation of Al-Ce and Al-Fe-Ce atomic groups,reduced Al-Fe atomic groups,and provided nucleation conditions for the formation of AlCe and AlFeCe phases.For Al-Fe alloys,since the total banding ability of structural unit FAl6 Fewas less than FAl3 Fe,so the Al6 Fe phase was formed preferentially.For Al-Fe-Ce alloy,because of FAl8 Fe4 Ce<FAl4 Ce<FAl6 Fe,therefore,small and short rod-like Al8 Fe4 Ce phase was preferentially formed,which consumed Fe atoms,reduced the formation of thick spicelike,spherical Al3 Fe and Al6 Fe phases.The bond force of the strongest bond of Al8 Fe4 Ce was similar to that of Al3 Fe,and Al4 Ce was similar to that of Al6 Fe.The strong and weak bond strength of Al4 Ce varied greatly,while the bond distribution of Al8 Fe4 Ce was more uniform,without weak bonding links.