Effects of Sc and Mn on microstructures and mechanical properties of Mg-Gd alloy

Two alloys of Mg-12.4Gd and Mg-12.5Gd-0.8Sc-1.4Mn were prepared. Hot extrusion and T5 heat treatment were conducted, and then the mechanical properties of the two alloys were tested at room and high temperatures. The effects of Sc, Mn on the microstructures of Mg-12.4Gd were investigated by optical microscopy, scanning electron microscopy and transmission electron microscopy. The results demonstrate that after hot-extrusion the alloying with Sc, Mn can efficaciously refine the grains of Mg-12.4Gd alloy; and increase the elongation at room and high temperatures after T5 heat treatment. But the strength at high temperature is not obviously improved.     

挤压态SiCw/1050A复合材料的强度预测

为了考察挤压态复合材料的性能,挤压铸造SiCw/1050A复合材料被热挤压。对复合材料中的组织结构参数进行了测定和分析,并采用混合法则对挤压态SiCw/1050A复合材料的强度进行了预测。结果表明,挤压导致复合材料中组织参数发生变化(包括晶须和基体),进而影响复合材料的性能。用修正的混合定律预测挤压态SiCw/1050A复合材料纵向强度时必须增大表征基体贡献的系数c到6左右才能得到满意的结果,表明基体强度是影响SiCw/1050A复合材料强度的一个重要因素。     

Microstructures and mechanical properties of Mg-Ce-Zn-Zr wrought alloy

Microstructures and mechanical properties of Mg-2.0 ?-0.7 % Zn-0.7% Zr alloy were studied. The results of scanning electron microscopy show that Mg12 Ce phase mainly distributes at the grain boundaries. The fine Mg12 Ce phase can apparently elevate recrystallization temperature by preventing the grain boundary migration. No dynamic recrystallization occurs during the hot-extrusion. The mechanical properties of as extruded specimens are σb=278.5MPa, δ=12.0%, while those of the specimens annealed at 250℃ for 100 h are σb=272.6 MPa, δ=11.3%, which indicate that the alloy has good mechanical properties at room temperature.     

铁基形状记忆合金0Cr12Ni6Mn16Si5的研制

探讨了0Cr12Ni6Mn16Si5形状记忆合金的工业化生产工艺,0Cr12Ni6Mn16Si5可以采用EF1+AOD+EF2进行冶炼.合金具有强的热敏感性和高温变形抗力,高温可加工热塑性温度区间比较窄,温度超过1*!100℃,塑性直线下降.铸锭的开锻温度为1*!080℃,终锻温度为900℃;锻造管坯只有采用挤压方法实施管材成型.挤压成型的毛管可以采用冷轧与冷拔相接合方法进一步加工成薄壁管.     

GH202镍基合金无缝管材的热挤压工艺

对沉淀强化型镍基高温合金GH202进行了热挤压工艺研究,以保持挤压变形区的热量平衡为依据,制定并优化了挤压工艺参数,开发并应用了专用挤压筒和润滑材料。结果表明,热挤压工艺适用于GH202合金无缝管制备,管材组织均匀,力学性能高,生产效率及成材率大幅度提高。     

热挤压镁合金AZ91的微观组织及其力学行为

研究了热挤压镁合金AZ91的微观组织以及在不同试验温度和不同的热处理条件下的拉伸力学性能.结果表明：热挤压可以显著减小AZ91合金的晶粒尺寸，其拉伸力学性能与试验温度密切相关；可以通过热处理来改善其拉伸力学性能，其中人工时效及固溶时效工艺均是改善和提高挤压后AZ91镁合金力学性能的有效途径.此外，利用扫描电镜分析了AZ91镁合金拉伸试样的断口形貌，并探讨了其拉伸断裂机制.     

热挤压Mg-3Sn-1Zn-xCu合金的显微组织与力学性能

研究了添加Cu对热挤压Mg-3Sn-1Zn合金显微组织和力学性能的影响。结果表明:添加少量Cu能显著细化热挤压Mg-3Sn-1Zn合金晶粒,同时在合金中形成具有高热稳定性的CuMgZn相,提高了合金的室温及高温强度和塑性。当Cu含量为0.5%时,热挤压Mg-3Sn-1Zn-0.5Cu合金的晶粒最细,为2.8 μm;其强度和塑性最高,室温屈服强度为241 MPa,伸长率为20.3%,150 ℃时屈服强度为128 MPa,室温拉伸力学性能优于挤压态AZ31B合金,高温强度优于铸态AE42合金。     

Effects of cerium on microstructure and mechanical properties of ZK60 alloy

ZK60-xcerium alloys were studied,where x mass fraction is 0, 0.52%, 0.94%, 1.51% and 1.98%, respectively. Influence of Ce contents and heat-treatment on microstructure and tensile properties was analyzed. The results show that cast ZK60 alloy containing no Ce has coarse crystal grains, and lots of segregation aggregates around the grain-boundary. However, the alloys containing Ce have refined grains, and grain-boundaries are purified at the same time. Obvious dynamic recrystallization occurs in tested alloys after hot-extrusion. Tensile strength heightens with the increase of Ce content, and grows higher after aging at 150℃ for 0 -24 h （T5 treatment）. Comparing tensile properties of investigated alloys in different states, it can be concluded that synthetical properties of the alloy with 1.51% Ce addition is the best of all. In extruded state, σb and δ of this alloy are 318.6 MPa and 14.4%, respectively. After aging for 24 h ,σb is 338.6 MPa and δ is 15.6%.     

Corrosion and mechanical properties of hot-extruded AZ31 magnesium alloys

AZ31 magnesium alloys were hot-extruded at 573 K and 623 K with extrusion ratio(λ) of 20,35 and 50.The corrosion and mechanical behavior of hot-extruded AZ31 were studied by galvanic tests and tensile tests.The microstructures of the studied AZ31 alloys were also investigated with optical microscope.The results show that,compared with the as-cast AZ31 alloy,the corrosion potentials of all hot-extruded AZ31 alloys are increased by 60 mV.Moreover,at the extrusion temperature of 623 K,the galvanic current o...     

半固态搅拌法制备B_4C_p/AZ91复合材料热挤压态的组织与性能

用半固态搅拌法结合热挤压工艺制备出了颗粒分布均匀、孔隙率低的B4Cp/AZ91颗粒增强镁基复合材料.在经过热挤压后,材料密度为1.873 g/cm3,0～100℃线膨胀系数为19×10-6K-1,抗拉强度为282.8 MPa.热挤压能显著提高复合材料的致密度,细化基体组织,改善颗粒分布状况,热挤压会对B4C颗粒造成损伤和形成小范围的团簇状聚集,由于挤压变形过程中的协调变形和基体合金的填充机制,不会对材料组织造成损伤,从断口形貌特征上可以确定颗粒与基体间形成了很强的界面结合.