净化处理对Mg-Gd-Y-Zr镁合金耐蚀性的影响(英文)

在真空和非真空条件下对Mg-Gd-Y-Zr镁合金进行过滤净化处理。利用OM和SEM方法分析合金中夹杂物的种类、形貌、尺寸分布和体积分数;利用盐雾实验和电化学测试研究Mg-Gd-Y-Zr镁合金中夹杂物对合金耐蚀性的影响。结果表明:过滤净化处理可以有效地去除合金中的夹杂物;通过净化处理,合金中的夹杂物平均尺寸从12.7μm减小到2.0μm,夹杂物的平均体积分数从0.30%降低到0.04%;随着合金中夹杂物尺寸的减小,盐雾腐蚀实验中合金的腐蚀速率从38.8g/(m2·d)减少到2.4g/(m2·d);在电化学实验中,腐蚀电流密度减小,极化电阻升高,Mg-Gd-Y-Zr镁合金的耐蚀性得到了提高。     

GW103K合金熔剂净化的研究

针对高强耐热的稀土镁合金净化困难、稀土元素损耗大的问题,采用自行开发的熔剂JDRJ-6对GW103K合金进行精炼,研究了不同YCl_3含量的熔剂对合金净化效果及Y元素损耗率的影响,并与熔剂JDMJ及RJ-6的综合效果进行了比较.结果表明,经熔剂JDRJ-6+2.5%的YCl_3精炼后,Y元素的损耗率和腐蚀速率分别下降至18.12%和0.837 mg·cm~(-2)·d~(-1),而抗拉强度、伸长率则分别提高至226.25 MPa和4.86%,达到了预期的净化效果.     

气体保护熔炼条件下Mg-Gd-Y-Zr合金的夹杂物

本文研究了气体保护条件下,常规熔铸的Mg-Gd-Y-Zr合金中夹杂物的形貌、分布及形成原因,并通过计算分析了夹杂物的沉降行为.结果表明,Mg-Gd-Y-Zr合金中有MgO或Y的氧化物为主的球状、簇状、不规则状、线状的复合夹杂物和含熔剂夹杂物,夹杂物的平均尺寸为12.7μm,平均体积分数为0.26%.夹杂物出现的频率随其尺寸增大而急剧减小,尺寸在20μm以下的夹杂物占夹杂物总体积接近85%,尺寸在45μm以下的夹杂物占96%.计算结果表明,夹杂物沉降速率与其尺寸和密度相关;夹杂物密度增大,可使镁合金中夹杂物的最大尺寸减小,计算得到的合金中最大夹杂物的尺寸与实验结果基本一致.     

镁合金纯净化研究新进展

阐述镁合金中的夹杂物种类及其危害,镁合金含有MgO、Mg3N2、MgS、α-Fe、MnAl6、Fe2(Si,B)、Fe3(Al,Si)、(Fe,Mn)3Si和(Fe,Mn)5Si3等非金属夹杂物及Fe、Cu和Ni等有害金属元素。非金属夹杂物会严重降低合金的强度和韧性;Fe等有害元素会大幅度增加镁合金的腐蚀速率。重点阐述镁合金双活性加硼熔剂除铁技术及其除铁效果。针对稀土镁合金的净化难题,介绍稀土镁合金的专用净化熔剂、MgO泡沫陶瓷过滤器及旋转喷吹等镁合金非熔剂净化方法。综述复合净化对镁合金力学性能、流动性及热裂性的影响,并展望镁合金净化技术的未来发展。     

熔剂净化对Mg-Gd-Y-Zr合金流动性的影响

研究了PJ-6、RJ-6+5%GdCl3、RJ-6+5%YCl3以及JDMJ+X%GdCl3、JDMJ+X%YCl3熔剂精炼对Mg-10Gd-3Y-Zr合金流动性的影响,并采用了定量分析方法对精炼后的流动性试样进行夹杂物分析.试验结果表明:JDMJ+5%YCl3精炼剂和RJ-6+5%GdCl3精炼剂能显著提高合金的流动性,相对无熔剂精炼,流动性试样长度分别由780mm增加至1270mm和1113mm.夹杂物分析结果表明:JDMJ+5%YCl3精炼剂和RJ-6+5%GdCl3精炼剂能有效去除合金中的夹杂物,降低熔体的粘度,显著提高合金流动性.     

添加稀土Er于熔剂中对铸态AZ91镁合金组织与性能的影响

研究了熔炼时在熔剂(42%MnCl2 53%LiCl 5?F2,质量分数,%)中添加稀土Er对铸态AZ91镁合金显微组织、力学性能、断口形貌以及腐蚀行为的影响。结果表明:在熔剂中添加稀土Er能够去除镁合金熔炼过程中产生的熔剂夹杂,净化镁合金熔体,提高铸态AZ91镁合金的拉伸性能和耐腐蚀性能;当熔剂中添加10%的稀土Er时,镁合金的抗拉强度σb和伸长率δ分别从156MPa和1.8%上升到最大值220MPa和4.1%;同时,镁合金在5%NaCl水溶液中的腐蚀速率从1.20mg/(cm2.d)下降到最小值0.15mg/(cm2.d);然而,随着稀土Er在熔剂中添加量的进一步提高,合金中开始有φ-(Al7ErMn5)和τ-(Al66.7Mg23.3Er10)等含有稀土Er的相生成,消耗了合金中的Al和Mn元素,改变了β-(Mg17Al12)相的形态;而且沿枝晶界附近分布的粗大φ-(Al7ErMn5)相降低了枝晶之间的结合力,使得合金的σb和δ下降;同时,部分网状的β-(Mg17Al12)相断裂,呈离散的块状,导致合金的腐蚀速率增加;熔剂中添加稀土Er不改变镁合金的断裂机理,断裂机制仍为准解理断裂。     

MnCl2对镁合金废旧料组织性能的影响

利用等离子发射光谱仪、金相分析、电镜、万能电子材料试验机、腐蚀试验等方法研究了含有不同量的MnCl2熔剂对镁合金废旧料的力学性能、组织、断口形貌以及腐蚀行为的影响。研究表明,MnCl2可以降低镁合金废旧料中的Fe含量,同时会增加镁合金的Mn量,使用含MnCl2的熔剂可将镁废旧料中的Fe含量降到0 0072%以下。采用含MnCl2的熔剂可以提高试样的σb和δ。当合金中的Mn量超过一定程度后,对镁合金的力学性能会产生不利的影响。金相观察表明,净化处理对断口形貌无明显的影响,不改变AZ91镁合金的断裂机理,断口均成准解理断裂。腐蚀试验表明,采用含30%MnCl2的熔剂可以使试样的腐蚀速率从20 9mg/(cm2·d)降到6 4mg/(cm2·d)。     

镁合金熔剂净化技术的研究进展

镁合金在熔炼过程中易产生大量的非金属夹杂物与金属夹杂物,严重降低了合金的力学性能和铸造流动性。镁合金熔剂净化法除杂成本低、效率高、操作方便、效果好,从而成为镁合金生产中普遍采用的净化工艺。本文阐述了镁合金中杂质的危害及其熔剂净化技术的研究现状,指出了熔剂净化工艺的不足和改进,提出了研究发展趋势。     

氧化硼除铁净化镁合金的研究

在镁合金熔剂JDMR中加入氧化硼净化镁合金液,使铁含量降低到0.002%左右.氧化硼最佳用量为0.61%,最佳处理温度735℃,最佳处理时间40min.处理后的镁合金腐蚀速率从15.1mg/(cm2·day)降低到0.4mg/(cm2·day).X衍射证明FeB的形成是氧化硼除铁的主要原因.最后从热力学和动力学角度分析了氧化硼除铁机制.     

低铝脱氧不锈钢夹杂物演变规律分析

为改善2205双相不锈钢的洁净度以及探明夹杂物的演变规律,在不影响连铸可浇性前提下,以2205不锈钢"70 t EAF-70 t TSR-LF-CC"工艺流程中的"TSR还原期-LF二次精炼"部分为研究背景,尝试低铝脱氧工艺,将成品铝的质量分数控制在0.004 5%左右,使钢液中的夹杂物向镁铝尖晶石、钙铝酸盐等类型演变。通过对钢液中其气体含量以及夹杂物成分进行统计分析,试验结果表明:精炼结束后钢液全氧的质量分数为18×10-6,钢液中的夹杂物固液比例为1,呈半固半液结构;精炼阶段夹杂物按"MgO·Al_2O_3→MgO/MgO·Al_2O_3→CaO-MgO-Al_2O_3"的路径进行转变,LF出站得到的CaO-MgO-Al_2O_3夹杂物与常规铝脱氧得到的CaO-MgO-Al_2O_3夹杂物在结构组成存在差异:核心为纯MgO,中间层MgO·Al_2O_3,外层3CaO·Al_2O_3。     

Purifying effect of new flux on magnesium alloy

1　INTRODUCTIONAsoneofthelighteststructurematerials ,mag nesiumalloysofferlightmass(ρ<2 g·cm- 3) ,specif icstrength (higherthanthatofthealuminumalloysandsteels) ,specificstiffness ,excellentmachinabili ty ,superiordampingandmagneticshieldingcapaci ties,whichleadstoagrowinginterestinmagnesiumanditsalloys .Inrecentyears ,magnesiumalloyshavebeenwidelyusedinaviation ,spaceflight,automobileandelectronicsindustries[1] .Since 1990 stheirappli cationhassteadilyextendedanditispredictedthatitwill…     

Influence of GdCl3 addition on purifying effectiveness and properties of Mg-10Gd-3Y-0.5Zr alloy

In order to improve the purifying efficiency of R J6 flux, 5% （mass fraction） GdCl3 was introduced into the flux for refining Mg-10Gd-3Y-0.5Zr （GW103K） alloy. The results show that the RJ6 flux containing 5% GdCl3 exhibits better adsorption ability to nonmetallic inclusions than the one without GdCl3. Moreover, the mechanical, corrosion properties and fluidity of the alloy refined with RJ6 flux and RJ6 flux containing 5% GdCl3 were investigated, respectively. It is found that these properties are improved to a certain degree due to the removal of nonmetallic inclusions in the alloy. Thermodynamic analysis and surface tension experiments indicate that the main reason can be ascribed to the decrease of the surface tension of the flux with 5% GdCl3, which promotes the combination of flux and nonmetallic inclusions.     

Effects of filter materials on microstructure and mechanical properties of AZ91

The present investigation studied the effects of different kinds of ceramic foam filters (CFF) incorporating gas bubbling on the microstructure and mechanical properties of virgin AZ91 alloys, and the reactions between filters and Mg melt during filtration. The results show that the purification process of CFF incorporating gas bubbling process can obviously improve the R m and A of AZ91 alloy, especially the A. Amongst the selected four kinds of CFF, the MgO filter is the most suitable for filtrating Mg melt, and the filtration effective sequence of four kinds of filtrating materials is as follows: MgOAl2O3ZrO2SiC. With MgO filter incorporating gas bubbling treatment under Ar flow rate of 2 L/min and temperature of 730 °C, the ultimate tensile strength R m and elongation A can be improved greatly from 175.3 MPa and 2.74% to 195.4 MPa and 4.54%, respectively. No inclusions are found on the fracture surface of the sample filtrated by MgO ceramic foam filter, and the fracture mode is quasicleavage crack.     

Purification technology of AZ91 magnesium alloy wastes

1　INTRODUCTIONBecausemagnesiumalloyhastheadvantagesoflowdensity ,highspecificstrengthandrigidity ,ex cellentdampingeffect,goodtolerancetoimpact ,ex cellentmachinabilityandpolishingability[1,2 ] ,itiswidelyusedinthefieldsofautomobilemanufactur ing ,aviationandspaceflight,communication ,opticinstrumentsandcomputermanufacturing[35] .How ever ,theyieldofmagnesiumalloyislowinthepro ductionofdiecasting .Atpresent ,theutilizationra tiocanonlybeabout 30 % 5 0 % .Intheprocessofdiecasting ,alargeq…     

Investigation of flux containing GdCl_3 on recycling Mg-Gd-Y-Zr scraps

The effects of GdCl_3 in flux on the loss of Gd,microstructure,mechanical properties,and corrosion resistance of Mg-Gd-Y-Zr(GW103K) scraps were investigated by ICE XRD,SEM and EDS.The results show that the loss of Gd in the alloy decreases with increasing GdCl_3 content in the flux,and the mechanism of GdCl_3 suppressing the loss of Gd was analyzed by thermodynamic theory.The optimal average mechanical properties could be obtained when the GdCl_3 content in the flux was 5% (mass fraction).Compared with t...     

Mg-3Al-2Sc合金显微组织与性能研究

采用熔剂保护法制备了Mg-3Al-2Sc合金,并进行热挤压,研究了添加Sc及热挤压后Mg-3Al-2Sc合金的组织与性能.结果表明,稀土Sc能够细化晶粒并形成新的Al3Sc相;热挤压后Mg-3Al-2Sc合金发生了局部动态再结晶,合金屈服强度和抗拉强度较AZ31镁合金的显著提高,拉伸断裂机制主要表现为准解理断裂,并有一定量的沿晶断裂.     

Novel approach of LY12 alloy brazing

The LY12 Al alloy was brazed with the adoption of the improved KF-CsF-AlF3 flux matching Ag-Al-Cu-Zn filler metal. The shear strength of brazed joint could reach 80% of that of the substrate and the tensile strength of butt brazed joint will be 70% of that of the substrate. This was the great progress against the traditional claim that Al alloy reinforced by heat treatment could not be brazed. The experimental results and theoretical analysis had proved that it was the key issue to remove the MgO oxide film below 503℃. The addition of rare earth La was the effective way to obtain better mechanical properties of the filler metal as well as brazed joints.     

磁场对AZ80镁合金凝固组织的影响

研究了在直流磁场及频率为10 Hz、30 Hz交流磁场作用下AZ80镁合金凝固组织、合金元素在晶内含量及合金硬度的变化。结果表明,AZ80镁合金经交流磁场处理后,晶粒明显细化,晶界变窄,夹杂物的尺寸显著减小;经直流磁场处理后,晶粒大小没有明显变化,但晶界变窄,夹杂物的尺寸减小。无论经交流磁场还是直流磁场处理后,Al和Zn在晶粒内部的含量均比未经磁场处理有了明显增加。此外,经磁场处理后,合金硬度有一定程度的提高。初步阐明了这些现象产生的原因。     

Non-flux purification behavior of AZ91 magnesium alloy

The effects of non-flux purification techniques on the mechanical properties and microstructure of AZ91 magnesium alloy were investigated by ICP,OM,XRD and SEM.The results show that Ar spraying with high flow rate could remove non-metallic inclusions and improve the mechanical properties of AZ91.The alloy obtains the best properties after argon spraying for 30 min at the melt temperature of 740 °C.The ceramic foam filter(CFF) could effectively improve the ultimate tensile strength and elongation of AZ91 alloy,especially the elongation,which increase with increasing pores per inch(ppi) and the thickness of CFF.Non-flux purification does not change the microstructure of AZ91 alloy.However,filtration has a certain effect on the fracture pattern of AZ91 alloy.To improve the mechanical properties effectively,both filtration and gas spraying should be utilized together.