Effect of platinum group metal addition on microstructure and corrosion behaviour of Ti–47·5 at-%Al
Effect of platinum group metal addition on microstructure and corrosion behaviour of Ti–47·5 at-%Al
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铂族金属添加对Ti–47·5 at-%Al显微组织和腐蚀行为的影响
DOI：
10.1179/1743278213y.0000000108
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
E. Lingen
中科院分区：
文献类型：
--
作者：
I. Mwamba;L. Cornish;E. Lingen
在添加1.0 at-%铂族金属（PGMs）的条件下，制备了ti - 47.5 at-%Al成分的普通钛铝化物和合金钛铝化物。在室温下，对铸态合金在5%、15%和25%的HCl溶液中进行电位扫描，并对含PGM合金的阴极改性自发钝化能力进行了评估。纯钛铝化物具有由α 2和γ交替片层和γ- tial相晶粒组成的双相组织。引入1·0 at-%的铂、钯和铱导致了新相的形成，在γ-TiAl相晶粒中发展得更多，并通过将腐蚀电位提高到更高的值而普遍提高了耐蚀性。在普通TiAl中加入铂族金属导致普通TiAl钝化区的腐蚀电位下降，表明PGM合金TiAl在5%和15wt -%HCl溶液中自发钝化。在25 wt-%的HCl溶液中，PGMs的加入改变了普通TiAl的透射区或活性区的阴极过程，由于没有扩展的钝化区，导致合金的溶解。PGM合金TiAl的阴极改性是由于PGM在TiAl合金表面的积累，同时提高了析氢效率，抑制了阳极溶解。
Plain and alloyed titanium aluminides of composition Ti–47·5 at-%Al were prepared with the addition of 1·0 at-% platinum group metals (PGMs). The as cast alloys were subjected to potentiodynamic scans in 5, 15 and 25 wt-%HCl solutions at room temperature, and the PGM containing alloys were assessed for their abilities to spontaneously passivate by cathodic modification. Plain titanium aluminide had a duplex microstructure consisting of lamellar (α 2 and γ alternating lamellae) and γ-TiAl phase grains. The introduction of 1·0 at-%PGMs (platinum, palladium and iridium) led to the formation of a new phase, developing more in the γ-TiAl phase grains and a general improvement of corrosion resistance by increasing the corrosion potential to nobler values. Platinum group metal additions to plain TiAl resulted in the corrosion potentials falling in the passive region of plain TiAl, indicating spontaneous passivation of PGM alloyed TiAl in 5 and 15 wt-%HCl solutions. In 25 wt-%HCl solution, the addition of PGMs shifted the cathodic process in the transpassive or active region of plain TiAl, resulting in either case in the dissolution of the alloy due to the absence of an extended passivation region. The cathodic modification of PGM alloyed TiAl occurred as a result of PGM accumulation on the surface of the TiAl alloys, which simultaneously improved the hydrogen evolution efficiency and inhibited anodic dissolution.