az3lb镁合金激光表面熔凝的分析word格式论文.docxVIP

平均腐蚀速率为 0.0108g!(cm2 ? 时，小于未处理母材的 0.0684 g!(cm2 ? h)和空气冷却熔凝层的 O.0324g1(cm2 ? h) 。这说明液氮冷却条件下，对续合金腐蚀性能的提高优于空气冷却条件 。激光熔凝 AZ31B 镇合金中容易出现的缺陷为裂纹、气孔和合金元素的 烧损。研究发现，裂纹主要是结晶裂纹，气孔 主要为氢气孔。关键词: AZ31B 馍合金，激光表面熔凝，冷却速度，耐蚀性，耐磨性III3STUDY ON THE LASER SURFACE MEl:fING OFAZ31BMAGNESIUM ALLOYABSTRACTAs Green Engineering Materials in 21st Century，magnesium alloy has great potentialities of application in industries like aviation ，spaceflight，auto and electronics for its unique excellent properties (low density，high specific strength and specific sti旺ness，etc.). But，ma伊esium alloy is limited to apply in industry widely to some extent due to the poor performance in wear resistance，corrosion resistance ，etc. 1n order to expand the magnesium alloys potential ，we have toadopt some technology to improve its wear resistance and corrosion resistance which is very important to the application of magnesium a11oy.Microstructure of alloy would be different when they soJidify out.Firstly，solidification tests tbat AZ31 magnesi山丁1 a110y cooled in air，wate几 quencb oil and liquid nitrogen are carried out. Effect of differert cooling velocity on microstructure and performance is studied ，and the cooling velocity of magnesium alloy is estimated. Secondly，ln order to improve the wear resistance and the corrosion resistance，surface of AZ31B magnesium alloy is melted usinga pulsed 500W Nd:YAG laser in two different cooling way: one group is cooled in air，and the other is in liquid nitrogen. Magnesium alloy and the laser melted layer are studied by OM，Vickers hardness tester，XRD，1CM，wear tester andelectromical tester from the following aspects: microstructure ，microhardness ，corrosion resistance and wear resistance.The results of magnesium alloy solidification tests show that magnesiumV?alloy is a11 consist of a-Mg and ?-Mg 17Al12 phase under different ∞olingconditions. The grains of magnesium alloy solidified in water are more 自nethan that solidified in air，and the quantity of ?-Mg )7