共查询到20条相似文献,搜索用时 109 毫秒
1.
激光熔凝温度场的变化对熔凝层性能有重要影响。目前,将温度场数值模拟及熔凝层性能结合的研究报道较少。对AZ91D镁合金进行激光熔凝,建立了熔凝温度场有限元模型,分析了激光熔凝过程温度场加热冷却的规律,并通过试验验证模型的准确性。分别采用扫描电镜、显微硬度计、共聚焦激光扫描显微镜及摩擦磨损试验机分析了激光熔凝层的形貌、硬度及摩擦学特性。结果表明:激光熔凝温度场呈动态分布,表现出典型的急热骤冷特征,激光熔凝层显微硬度由表及里呈梯度分布,较好地验证了激光熔池的深度,熔凝层显微硬度均值为基体的1.4倍;激光熔凝层磨损量仅为基体的1/3,耐磨性较基体大幅提高,熔凝层及基体的磨损机制主要为磨粒磨损。 相似文献
2.
3.
4.
5.
镁合金微弧氧化陶瓷膜的微观结构、相成分和耐腐蚀性能 总被引:6,自引:1,他引:6
为获得耐腐蚀性优良的镁合金表面膜层,在含5 g/L硅酸钠、2 g/L磷酸钠和1 g/L氢氧化钠的复合溶液中,用自制设备对AZ91D镁合金进行了微弧氧化.利用扫描电镜和X射线衍射分析了AZ91D 镁合金表面微弧氧化陶瓷膜的表面形貌、截面结构和相组成.结果表明:AZ91D 微弧氧化陶瓷膜由疏松层和致密层组成,疏松层陶瓷膜疏松,厚度较大,且存在一些孔洞;致密层陶瓷膜与基体金属结合紧密,陶瓷膜主要由MgO,Mg2SiO4,Mg3(PO4)2和MgAl2O4组成.在3.5%的NaCl溶液中,微弧氧化陶瓷膜的自腐蚀电位为-1 390 mV,而镁合金基体的为-1 540 mV,表明经微弧氧化处理后AZ91D 镁合金的耐蚀性有较大提高. 相似文献
6.
7.
8.
9.
镁合金微弧氧化膜结构及耐蚀性的初步研究 总被引:14,自引:2,他引:14
空气中由于AZ91D镁合金耐腐蚀性差,影响实际应用.为了弄清腐蚀原因,增加应用效果,作者利用扫描电镜和X射线衍射分析了AZ91D镁合金表面微弧氧化膜的形貌、结构和相组成,并对氧化膜的耐蚀性作了初步试验分析.研究表明,AZ91D微弧氧化膜呈3层结构,外层氧化膜存在一些孔洞;中间层氧化膜疏松、具有较大厚度;内层氧化膜与基体金属结合紧密.氧化膜主要由MgO,MgSiO3,MgAl2O4,Mg3(PO4)2组成.经1周3%NaCl溶液浸泡试验,结果表明微弧氧化膜可以较大程度地提高AZ91D镁合金的耐蚀性,但氧化膜表面富含Si,P的颗粒是易发生腐蚀的电化学活性点,导致氧化膜发生局部腐蚀. 相似文献
10.
11.
12.
13.
Laser Surface Strengthening Process of Al-Si Base Alloy 总被引:2,自引:0,他引:2
With a laser beam, the surface remelting/resolidifying treatment of ZL108 alloy was studied. Test results showed that a compact remelting layer was obtained with appropriate laser processing conditions and a suitable surface coating for laser energy absorption. The eutectic silicon phase in the laser-treating zone changed from the shape of thick-plate (stripe) into the very small grains, the structure was extremely fined, the hardness and wear resistance were improved greatly compared with that of the base alloy. A laser -treating layer, which is 3.5 mm thick and 5 mm wide, could be obtained. 相似文献
14.
激光重熔处理对渗硼层脆性的影响 总被引:5,自引:0,他引:5
利用两种工艺方案对渗硼层进行了激光重熔处理,并通过声发射技术对表层脆性进行了定量测试。结果表明,激光重熔处理在不同程度上降低了渗硼层的脆性,相对脆性最大降低了71.3%。通过改变渗硼层的形貌和组织结构,消除FeB和渗层内的缺陷,改善界面结合强度和适当降低表层硬度从而使硼原子得到重新分布等方式均能降低表层脆性。 相似文献
15.
采用半固态触变锻造技术成形铝合金构件,容易实现轻量化、低成本、短流程制造,因此在汽车、航空航天等领域应用广泛,但是对于高强铝合金复杂形状构件触变锻造存在半固态坯料制坯工序复杂、制件固液偏析严重和力学性能较弱等问题。基于SIMA制坯方法,提出了分级热处理、快速感应重熔和梯度等温处理等重熔工艺以及触变-塑变复合成形等新成形技术,优化了变形铝合金二次重熔半固态组织调控和触变锻造技术,获得了良好的半固态球晶组织并成形出合格的制件,最后提出了铝合金触变锻造成形中仍需解决的问题和发展方向。 相似文献
16.
17.
18.
高压成型铝硅系列合金晶粒组织控制及其强化技术的研究进展 总被引:1,自引:0,他引:1
综述了高压条件下的铝硅系列合金的晶粒组织控制及其强化技术,介绍了我国高压成型的产业化情况.高压条件下结晶的零件性能高低主要取决于结晶前的液态金属结构和成型过程中的结晶条件,零件强化的主要工艺措施有热速处理、细化处理以及压力下结晶.开展铝硅合金结晶的晶粒组织控制模拟仿真技术研究的理论主要是基于第一性原理和物理统计学理论,根据Monte-carlo模型和CA模型进行.结合高压成型实际生产工艺,说明了高压成型的晶粒组织控制的可行性. 相似文献
19.
In vitro corrosion behaviour of Mg alloys in a phosphate buffered solution for bone implant application 总被引:5,自引:0,他引:5
Xu L Zhang E Yin D Zeng S Yang K 《Journal of materials science. Materials in medicine》2008,19(3):1017-1025
The corrosion behaviour of Mg–Mn and Mg–Mn–Zn magnesium alloy in a phosphate buffered simulated body fluid (SBF) has been
investigated by electrochemical testing and weight loss experiment for bone implant application. Long passivation stage and
noble breakdown potential in the polarization curves indicated that a passive layer could be rapidly formed on the surface
of magnesium alloy in the phosphate buffered SBF, which in turn can protect magnesium from fast corrosion. Surfaces of the
immersed magnesium alloy were characterized by SEM, EDS, SAXS and XPS. Results have shown that Mg–Mn and Mg–Mn–Zn alloy were
covered completely by an amorphous Mg-containing phosphate reaction layer after 24 h immersion. The corrosion behaviour of
magnesium alloys can be described by the dissolving of magnesium through the reaction between magnesium and solution and the
precipitating of Mg-containing phosphate on the magnesium surface. Weight loss rate and weight gain rate results have indicated
that magnesium alloys were corroded seriously at the first 48 h while Mg-containing phosphate precipitated fast on the surface
of magnesium alloy. After 48–96 h immersion, the corrosion reaction and the precipitation reaction reach a stable stage, displaying
that the phosphate layer on magnesium surface, especially Zn-containing phosphate layer could provide effective protection
for magnesium alloy. 相似文献
20.
Semi-solid processing of magnesium alloys is generally based on conventional magnesium-based casting alloys such as Mg–Al series. However, these casting alloys do not give such high mechanical properties as the alloys that are conventionally wrought such as Mg–Zn series. In this paper, a ZK60 magnesium alloy with the addition of Y was thixoforged. The semi-solid thermal transformation (SSTT) route and the recrystallisation and partial melting (RAP) route were used to obtain the semi-solid feedstocks for thixoforging. Microstructural evolution during partial remelting was studied at temperatures for times. Tensile mechanical properties of thixoforged components at room temperature were examined. Results show that a fine spheroidal microstructure can be obtained by the RAP route. Compared to the RAP route, the SSTT alloy shows coarsened solid grains with a relatively high proportion of intragranular liquid droplets. With prolonged holding time, the solid grain sizes of the SSTT alloy and the RAP alloy increased. Coalescence was dominant in the SSTT alloy and Ostwald ripening was dominant in the RAP alloy. Thixoforging for the SSTT alloy and the RAP alloy resulted in successful filling of the die. The tensile properties of the thixoforged RAP alloy were satisfactory and exceeded those of the thixoforged SSTT alloy. However, the mechanical properties of both the thixoforged SSTT alloy and the thixoforged RAP alloy decreased with prolonged holding time. 相似文献