本文選題：Mg-Al-Y合金　切入點：第一原理計算　出處：《中國有色金屬學(xué)報》2015年12期 　論文類型：期刊論文

【摘要】：通過基于密度泛函理論的第一原理計算方法,對Mg-Al-Y合金中的主要強化相,即Al_2Y和Al_3Y的相穩(wěn)定性、電子結(jié)構(gòu)、彈性性質(zhì)以及熱力學(xué)性質(zhì)進(jìn)行計算。相生成熱的計算結(jié)果表明:Al_2Y和Al_3Y均可穩(wěn)定存在,Al_2Y的結(jié)構(gòu)穩(wěn)定性更強,因此,在合金的凝固過程中,Al_2Y優(yōu)先析出。Al_2Y和Al_3Y的電子態(tài)密度(DOS)和差分電荷密度計算的結(jié)果表明:Al_2Y和Al_3Y兩相可以穩(wěn)定存在的內(nèi)在本質(zhì)在于Al原子與Y原子的價電子軌道發(fā)生強烈的相互作用,形成了spd雜化。兩相內(nèi)的原子成鍵均為共價鍵、離子鍵和金屬鍵。體模量B、剪切模量G、彈性模量E、泊松比v和各向異性因子A等力學(xué)性質(zhì)參數(shù)的計算結(jié)果表明:這兩種相為強硬的脆性相并都為各向同性,因此,具有相似的強化效果。兩相熔點較高表明其具有很好的熱穩(wěn)定性,能夠提高合金的高溫性能。聲子譜和聲子態(tài)密度計算以及德拜溫度的計算結(jié)果進(jìn)一步驗證了兩相具有結(jié)構(gòu)穩(wěn)定性較高。兩相的熱力學(xué)性質(zhì)符合一般熱力學(xué)規(guī)律,其中自由能的計算結(jié)果表明:兩相的穩(wěn)定性順序沒有發(fā)生變化。隨著溫度的升高,Al_2Y的結(jié)構(gòu)穩(wěn)定性仍強于Al_3Y的。
[Abstract]:Based on the density functional theory (DFT), the phase stability and electronic structure of the main strengthened phases in Mg-Al-Y alloys, namely, Al_2Y and Al_3Y, are studied. The calculation results of heat of generation show that the structure stability of Al2Y and Al_3Y is stronger than that of Al2Y. The results of electron density of states (DOS) and differential charge density (Dos) calculation of Alsta2Y and Al_3Y during the solidification of the alloy show that the intrinsic nature of the stable existence of the two phases in the Al and Y atoms lies in the valence electron orbital generation of the Al and Y atoms. Strong interaction, Spd hybrid is formed. The atoms in the two phases are covalent bonds. The calculated results of mechanical properties such as bulk modulus B, shear modulus G, elastic modulus E, Poisson's ratio v and anisotropy factor A show that these two phases are both hard brittle and isotropic. It has a similar strengthening effect. The high melting point of two phases indicates that it has good thermal stability. The calculation results of phonon spectrum, phonon density of states and Debye temperature show that the structure stability of the two phases is higher. The thermodynamic properties of the two phases conform to the general thermodynamic law. The calculation results of free energy show that the stability order of the two phases is not changed, and the structure stability of Al2Y is still stronger than that of Al_3Y with the increase of temperature.
【作者單位】： 沈陽工業(yè)大學(xué)材料科學(xué)與工程學(xué)院;
【基金】：2013遼寧省科技廳各類別項目(2013201018)
【分類號】：TG146.22
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本文編號：1632122