Modification of Primary Mg2Si in Mg-4Si Alloys with Antimony

The refinement in size and modification in morphology for primary Mg₂Si depended significantly on Sb contents in Mg-4Si alloys. Adding Sb into melts evidently increased the nucleus numbers of primary Mg₂Si crystals. Moreover, the preferential growth along $ \left\langle { 100} \right\rangle $ directions in dendritic crystals was restricted greatly due to the Si sites being substituted by Sb in Mg₂Si lattices, resulting in modified primary Mg₂Si crystals growing to octahedral morphology surrounded by {111} planes; therefore, the modification process could be called adsorption and poisoning mechanisms.     

新型高强度弹簧钢40Si2CrNi2MoV、44Si2CrV的疲劳性能研究

采用旋转弯曲疲劳试验方法研究了新型高强度弹簧钢40Si2CrNi2MoV、44Si2CrV钢的疲劳性能,试验结果表明,在试样回火温度420℃时,44Si2CrV钢试样的疲劳寿命高于40Si2CrNi2MoV钢;而当回火温度480℃或560℃时,40Si2CrNi2MoV钢的疲劳寿命高于44Si2CrV钢。经各种不同的温度回火处理而使其强度接近时,40Si2CrNi2MoV、44Si2CrV钢试样的疲劳寿命均高于60Si2CrVA钢。