论文部分内容阅读
为探讨改善Mg-Al合金耐热性能的途径,开发性能优良、价格廉价的镁合金,采用硅合金化的方法,研究不同硅含量时Mg-9%Al-x%Si合金(x=3,6和9)的凝固组织和室温力学性能。结果表明,三种铸态合金均由-αMg相、Mg2Si和-βMg17Al12组成。Mg2Si呈树枝状,且随硅含量提高,枝晶越发达,体积分数也增大。随Si量的增多,合金的抗拉强度、屈服强度和伸长率下降,硬度提高。经过415℃×12h固溶处理后,Mg2Si相的尖角钝化,部分Mg2Si相呈形状规整的椭圆形。固溶处理使Mg-9%Al-6%Si合金的抗拉强度和伸长率提高,时效可提高合金强度和硬度。Mg2Si相固液界面生长前沿的溶质边界层造成的成分过冷区及生长晶面上不同地方之间硅元素过饱和度的差异造成Mg2Si晶体凝固界面失稳,从而使得本属于小晶面生长的Mg2Si相在实际生长条件下为枝晶生长方式。
In order to explore the ways to improve the heat resistance of Mg-Al alloy, magnesium alloys with excellent properties and low cost were developed. The effects of different silicon contents on the microstructures of Mg-9% Al-x% Si alloy (x = 6 and 9) of the solidified tissue and room temperature mechanical properties. The results show that the three as-cast alloys are composed of-αMg phase, Mg2Si and -βMg17Al12. Mg2Si was dendritic. With the increase of silicon content, the dendrite became more developed and the volume fraction also increased. As the amount of Si increases, the tensile strength, yield strength and elongation of the alloy decrease, and the hardness increases. After 415 ℃ × 12h solution treatment, Mg2Si phase sharp corners passivation, some Mg2Si phase shape oval-shaped. The solution treatment increases the tensile strength and elongation of the Mg-9% Al-6% Si alloy, and the aging improves the strength and hardness of the alloy. Mg2Si solid-liquid interface growth front of the solute boundary layer caused by the composition of supercooling and growth of the crystal surface between different places on the silicon supersaturation caused by the instability of the interface solidification of Mg2Si crystal, making the crystal growth of this small face Mg2Si phase dendrite growth under the actual growth conditions.