Ca对AE41合金压蠕变行为的影响

采用自制的实验装置研究了Ca对AE41(Mg-4Al-RE)合金压蠕变行为的影响,并利用光学显微镜、XRD和SEM(带EDX)对合金压蠕变前后的组织进行了分析.结果表明:在150℃、100 MPa条件下,随着Ca含量的增加,AEX(Mg-Al-RE-Ca)合金的第一阶段的压蠕变量、稳态蠕变速率及总蠕变量不断减小,抗蠕变性能不断提高.铸态AE41合金由α-Mg基体和Al11Nd3相组成.在高温蠕变条件下,因针状Al11Nd3相不稳定易发生分解,导致AE41合金抗蠕变能力下降.在AEAI合金中加人Ca后,针状Al11Nd3逐渐被Al2Ca和Al2Nd代替.分布在晶界的Al2Ca相有很高的热稳定性,提高了AEX合金的抗蠕变性能.     

AZ81镁合金压入蠕变性能

采用自制装置对AZ81镁合金进行压入蠕变实验,通过建立稳态压入蠕变本构模型分析合金的蠕变机制,利用扫描电镜(SEM)和X射线衍射(XRD)等方法研究合金蠕变前后的组织和成分。结果表明:压铸AZ81合金在稳态蠕变阶段的应力指数n为2.08,蠕变激活能QC为87.26 kJ/mol;蠕变诱导β相首先由非连续方式析出,到达一定程度后连续析出;沿晶界析出的β相导致合金抗蠕变性能降低;蠕变温度越高,基体和析出相的晶粒尺寸越大;压铸AZ81合金的压入蠕变机制为晶界扩散主导的位错交滑移运动。     

T4和T6热处理参数对AZ91+x％La镁合金组织和性能的影响

在不同的T4和T6热处理参数下,对AZ91+x％La镁合金在的组织和硬度的变化进行了研究.结果表明,T4(410℃+16 h)固溶处理后,由于合金的大部分β相都溶入基体中,硬度比铸态时有所下降;T6( 170℃+24 h)时效处理后,基体上析出了大量晶界分布或在α相晶粒内的层片状β-Mg17Al12相,合金硬度得到显著提高,且AZ91 +0.16％ La镁合金时效态试样的硬度最高,可达138 HV.     

热处理对搅拌摩擦加工AZ91镁合金显微组织和力学性能的影响

对AZ91镁合金铸板进行搅拌摩擦加工,研究热处理对被加工材料组织和力学性能的影响。结果表明,经413℃保温16h固溶处理后,铸态合金晶界处粗大的网状β-Mg17Al12相基本溶入α-Mg基体中。在搅拌摩擦加工过程中,组织发生明显细化,产生细小的等轴状再结晶晶粒。预先固溶处理可使摩擦加工合金晶界处少量未溶β-Mg17Al12相全部溶入基体。随后时效处理导致β-Mg17Al12相以两种方式析出,时效初期以晶界处非连续析出为主,然后再发生晶粒内部的连续析出。时效处理可较大程度地提高合金的硬度,以16h最为显著,搅拌区平均显微硬度的最大值为118.4HV。预先固溶处理可以提高搅拌摩擦加工合金的塑性,伸长率为31.5%;随后时效处理(16h)则可以大幅度提高合金的抗拉强度,由搅拌摩擦加工板的265 MPa增至340 MPa。     

流变压铸AM60镁合金在固溶处理过程中的组织演变

采用光学显微镜(0M)、扫描电镜(SEM),研究了固溶处理对流变压铸AM60镁合金组织及硬度的影响.结果表明,流变压铸成形的AM60镁合金在430 ℃固溶处理24 h后,AM60镁合金晶界及枝晶间的粗大网状β-Mg17Al12相几乎全部消除,只剩少量、不连续状的β-Mg17Al12相残留在晶界,α-Mg基体中出现少量细小颗粒状β-Mg17Al12相,α-Mg基体中的A1含量显著增加.而且,随着固溶时间的延长,流变压铸成形AM60镁合金组织中的初生颗粒与二次凝固区颗粒出现合并长大现象,它们的长大速率都随固溶时间的延长而降低,随固溶温度的升高而增大.     

Ti3Al基合金的热处理显微组织与蠕变性能

对Ti_3Al基合金Ti_3Al-26M,Ti_3Al-11.5M和Ti_3Al-22M(wt%)(M=Nb,Mo,V)的热处理与显微组织和显微组织与蠕变性能之间的关系进行了探讨。结果表明:同一合金在不同热处理条件下的显微组织具有不同的特征和尺寸,而在同一热处理条件下的3种合金显微组织特征相同,只是晶粒的尺寸不同。高温蠕变性能测定表明,Ti_3Al-26M合金的蠕变性能优于Ti_3Al-11.5M和Ti_3Al-22M合金。Ti_3Al-26M合金经β固溶处理的魏氏组织的蠕变性能最好,经α_2+β固溶+时效和工厂处理的等轴组织蠕变性能次之。Ti_3Al-26M合金α_2+β固溶+时效状态的稳态蠕变速率与温度和应力的关系研究表明。随着温度和应力的增加稳态蠕变速率明显增加,并且随温度影响更为明显。     

Mg-4Al-RE-0．8Ca-0．8Si合金压入蠕变性能研究

用自制的装置对Mg-4Al-RE-0.8Ca-0.8Si(AECS410808)合金进行压入蠕变试验,用OM、SEM和EDS等方法对合金实验前后的组织成分进行分析.结果表明,AECS410808合金的稳态蠕变速率随温度或压力的增加而增大.稳态阶段的蠕变速率的对数lnε分别与应力的对数lnσ和温度倒数1/T均有较好的线件关系.在不同温度和应力条件下,合金的应力指数和蠕变表观激活能相差不大,其均值分别为n=3.04和Q=30.06 kJ/mol.AECS410808合金在稳态蠕变阶段的蠕变机制为晶界滑移主导的位错粘滞运动.合金中的Ca溶入β-Mg17Al12相中,提高了β的熔点,弥散分布的Mg2Si的枝臂伸入与其相邻的α-Mg晶粒内部,对晶粒产生了良好的钉扎作用,阻碍了晶界的滑移和佗错的运动,从而提高了合金的抗蠕变性能.     

AE42和Mg-Al-RE-Ca合金的压入抗蠕变性能

用压入蠕变的方法研究了AE42合金和在AE41合金中加入0．4％-1．2％Ca的（质量分数，下同）Mg-Al-RE-Ca合金的抗蠕变性能，并利用光学显微镜，XRD和SEM（带EDS）对合金蠕变前后的组织结构进行了分析。结果表明：随着Ca添加量的提高，Mg-Al-RE-Ca合金的压入抗蠕变性能也不断提高，Mg-Al-RE-Ca合金在150℃和175℃时的压入抗蠕变性能优于AE42合金。压入蠕变前后的组织结构分析表明：AE42合金中Al11Nd3相在高温下不稳定会分解，造成抗蠕变性能下降：而在稀土含量相对少的Mg-Al-RE-Ca合金中，形成热稳定性好的Al2Ca，改善了合金的抗蠕变性能。     

Mg-4Al-2RE合金压缩蠕变性能和组织研究

采用自制实验装置研究了铸态Mg-4Al-2RE合金在温度125~175℃、压力88~112MPa的压缩蠕变行为,利用扫描电镜、X射线衍射仪和能谱分析仪对该合金压蠕变前后的组织形貌和相成分进行了分析。结果表明:随温度和应力的升高,合金的压蠕变量增大。Mg-4Al-2RE合金铸态组织为α-Mg基体、Al11Nd3相和Al2Nd相;高温压蠕变时Al11Nd3相不稳定易发生分解,使晶界原子扩撒加剧,晶界明显滑移,致使合金的抗高温蠕变性变差。在175℃、100~112MPa条件下,该合金快速进入加速蠕变阶段,出现了沿晶蠕变断裂现象。     

固溶时效对挤压态AM60镁合金显微组织与硬度的影响

以挤压态AM60镁合金为对象,研究了固溶时效处理对合金显微组织和硬度的影响。结果表明,固溶处理5 h后,呈网状连续分布在晶界处的Mg17Al12基本全部溶入α-Mg基体中,时效处理后再以颗粒的形式重新析出并弥散分布在晶粒内部。固溶处理后,AM60镁合金的硬度有所下降,固溶7 h时硬度达到最低值71 HBS。随着时效时间的延长,合金的硬度先升高后降低,时效处理3 h时硬度达到最大值。     

Creep resistance of Mg-4 %Al-2 %RE-2 ? alloy

The creep resistance of the alloy Mg-4Al-2RE-2Ca（AEC422） and the base alloy AE42 was studied. The results reveal that the precipitated phases of AEC422 consist of Al2La and Al2Ca by contrast with the precipitated phase Al11La3 in AE42, which is instable and decomposes to A1l2La and Al at high temperature. Creep resistance of AEC422 is significantly improved compared with that of AE42. The microstructure of AEC422 has no obvious changes after creep test at 175℃ and 70MPa, as compared to that before creep test, indicating that Al2La and Al2Ca have high thermal stability. Especially Al2Ca phase largely increases the strength of the grain boundaries in AEC422, which accounts for the creep resistance improvement.     

挤压和热处理过程中AZ91镁合金的组织变化(英文)

对AZ91镁合金在均质化热处理、热挤压和时效处理中的组织演化规律进行研究。研究结果表明,在铸态组织中存在离异共晶和固态析出两种β-Mg17Al12相。在最佳的均质化处理(380℃,15h)过程中,β-Mg17Al12相大部分溶解到α-Mg基体中,并且晶粒细小。在热挤压过程中发生动态再结晶以及由此产生的晶粒细化。而时效处理之后则出现平行于挤压方向的带状β-Mg17Al12相析出,这应该是由于在挤压过程中把原始铸造偏析挤扁拉长而造成的。另外,根据实验结果,详细地讨论了均质化和时效处理的温度、保温时间以及挤压工艺参数对AZ91镁合金的组织变化产生的影响。     

喷射成形Mg-9Al-xZn合金的微观组织演变

利用喷射成形技术制备AZ91、AZ92和AZ93镁合金沉积柱坯,并对其微观组织演变进行观察.结果表明:铸态普通凝固AZ91合金的晶粒粗大,脆性β-Mg17Al12相连续分布成网状结构;而喷射成形AZ91、AZ92和AZ93合金的组织均匀,晶粒被充分细化,β-Mg17Al12相的网状结构被打破;喷射沉积快速凝固条件下高的冷却速率促进了过饱和α-Mg固溶体组织的形成,使得偏析相减少,形态改善;Zn含量的增加降低了Al在Mg中的溶解极限,促进了β-Mg17Al12相在晶界的析出及α-Mg+β-Mg17Al12离异共晶组织的形成;Zn元素的偏析倾向为激活成分过冷区内的形核质点提供了驱动力,从而阻碍了晶粒长大.     

热处理对快速凝固ZK60镁合金薄带组织和硬度的影响

采用单辊甩带法制备了ZK60镁合金薄带,研究了不同条件热处理薄带的组织和显微硬度。结果表明,薄带由晶粒尺寸8μm的等轴α-Mg、球状β′2相和少量杆状β′1相组成;热处理温度300℃时,晶粒无长大;温度300℃时,晶粒显著长大。原始薄带显微硬度约为50HV,300℃×2h热处理后显微硬度值最大约为80HV;β′1和β′2相的弥散强化作用是薄带硬度提高的内在原因。     

Microstructure,mechanical properties and creep resistance of Mg–(8%–12%)Zn–(2%–6%)Al alloys

The microstructural characteristics, mechanical properties and creep resistance of Mg–(8%–12%)Zn–(2%–6%)Al alloys were investigated to get a better overall understanding of these series alloys. The results indicate that the microstructure of the alloys ZA82, ZA102 and ZA122 with the mass ratio of Zn to Al of 4–6 is mainly composed of α-Mg matrix and two different morphologies of precipitates (block τ-Mg₃₂(Al, Zn)₄₉ and dense lamellar ε-Mg₅₁Zn₂₀), the alloys ZA84, ZA104 and ZA124 with the mass ratio of 2–3 contain α-Mg matrix and only block τ phases, and the alloys ZA86, ZA106 and ZA126 with the mass ratio of 1–2 consist of α-Mg matrix, block τ precipitates, lamellar ?-Al₂Mg₅Zn₂ eutectics and flocculent β-Mg₁₇Al₁₂ compounds. The alloys studied with the mass ratio of Zn to Al of 2–3 exhibit high creep resistance, and the alloy ZA124 with the continuous network of τ precipitating along grain boundaries shows the highest creep resistance.     

Ca对Mg-5Al-1Bi合金显微组织和力学性能的影响

使用X射线衍射仪、金相显微镜、扫描电镜、能谱仪及力学性能测试等试验手段,研究了Ca含量对铸态Mg-5Al-1Bi镁合金显微组织和力学性能的影响。结果表明,铸态Mg-5Al-1Bi镁合金由α-Mg基体和β-Mg17Al12相组成,加入Ca后,合金晶粒细化,β-Mg17Al12相的数量减少,由连续变得较为分散。当Ca含量达到3%时,合金中生成新的第二相Al2Ca。高熔点相Al2Ca在高温条件下能钉扎晶界,阻碍晶界滑移,有利于提高合金的高温蠕变性能。合金硬度和屈服强度随着Ca含量的增加而提高,而抗拉强度和伸长率下降。     

Influence of aging modes on microstructure and mechanical properties of AZ80 magnesium alloy

The microstructure and mechanical properties of AZ80 magnesium alloy after solid solution and aging treatments were studied by using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy(SEM) as well as tensile testing. The results indicated that β-Mg17Al12 phase was getting to distribute discontinuously along the grain boundary after treated at 395℃ ageing for 12 h followed by water-cooling, but it did not dissolve into α-Mg completely. The residual β-Mg17Al12 phase distributed along the grain boundary and had block-like or island shapes. The size of α-Mg was getting to be coarsening but not significantly. The β-Mg17Al12 precipitates appeared in discontinuous and continuous patterns from supersaturated α-Mg solid solution after aged at 200℃. The precipitation patterns were associated with the aging time essentially. The tensile strength and elongation of the alloy increased significantly but the hardness and yield strength decreased after solid solution treatment. However, with the prolonging of aging time, the hardness and strength of alloy increased while the ductility decreased.     

光纤激光焊接AZ91D镁合金接头微观组织特征

采用光纤激光焊接AZ91D镁合金,借助金相显微镜、X射线衍射仪、扫描电镜、透射电镜分别对焊接接头的微观组织结构、相组成、断口形貌进行分析.结果表明:光纤激光焊接AZ91D镁合金,能够得到无明显缺陷的焊接接头,焊缝组织为细小的柱状晶组织,接头热影响区小.焊缝组织由过饱和α-Mg固溶体和Al_2Mg相组成,焊缝金属冷却速度较快,没有β-Mg_(17)Al_(12)脆性相析出.α-Mg晶内和晶界上有少量Al_2Mg析出物,且存在大量位错线和位错胞.断口特征为韧脆混合断裂形式,有微小裂纹存在.     

The microstructure, tensile properties, and creep behavior of as-cast Mg–(1–10)%Sn alloys

The microstructure, tensile properties, and creep behavior of Mg–(1–10)wt%Sn alloys were studied in this paper. The microstructure of as-cast Mg–Sn alloys consisted of dendrite -Mg and second Mg₂Sn phases and the secondary dendrite arm spacing (DAS) of the -Mg phase was decreased with the increase of tin content. The micro-hardness of the alloys increased when tin content rises, while the greatest tensile and elongation were exhibited by Mg–5 wt%Sn. The indentation creep experiments were conducted at 150 °C for applied loads of 30 kg, it suggested that the indentation creep resistance of Mg–Sn alloys could be obviously improved with the increase of tin content, and Mg–10%Sn alloy had better indentation creep resistance than that of AE42.