Phase relations and crystal structure study in various Ti, Al and Si-based systems

Titanlegierungen haben ein breites Sortiment von Anwendungen. Sie werden nicht nur in der Turbinen- und Automobilindustrie verwendet sondern auch für Anwendungen in der Raumfahrt. Außerdem sind sie potentielle Kandidaten für Wasserstoffspeicherung. In vielen Fällen werden sie zusammen mit Aluminium verwendet. Beide Metalle, Titan und Aluminium, haben den Vorteil, dass sie leicht sind und daher wertvolle Bestandteile hochwarmfester Legierungen darstellen. Materialien, basierend auf Aluminium, werden in Industrie sowie für Geräte im Haushalt verwendet. Silicium ist ein sehr wichtiger Legierungspartner und Legierungen mit Silicium sind vielversprechende Materialien für Einsätze bei hohen Temperaturen weil sie einen hohen Schmelzpunkt in Kombination mit hoher Oxidationsbeständigkeit aufweisen. Für die Auswahl und das Design von Materialien hoher Qualität ist die genaue Kenntnis von Phasengleichgewichten und Kristallstrukturen wichtig. Der Zweck dieser wissenschaftlichen Arbeit war daher, Information über Kristallstruktur und Phasenbeziehungen in den Systemen mit Ti, Al und Si bereit zu stellen aber auch Inkonsistenzen in der Literatur zu klären. Obwohl das Ti-Ni-Al-system in der Vergangenheit gründlich untersucht wurde, bestanden etliche Probleme, die in dieser Arbeit mit Hilfe von XRD, kombiniert mit Neutronenpulverstreuung aber auch mittels EPMA-analysen geklärt werden konnten. Weiters wurden zwei Vierphasenreaktionen vom Übergangstyp ermittelt. Die Kristallstruktur von den zwei Verbindungen in der Al-reichen Zone (τ5-TiNi2-xAl5, x = 0.48) und der Ti-reichen Zone [τ6-Ti2(Ti,Ni,Al)3] des Ti-Ni-Al-systems wurde mittels Röntgenpulverdiffraktion kombiniert mit Einkristalluntersuchungen und Neutronenpulverdiffraktion gelöst. Zusätzlich wurden spezielle Phasenverbindungen die der Ti-reichen Phase [τ6-Ti2(Ti,Ni,Al)3] artverwandt sind geklärt und in dieser Studie darüber berichtet. Die Kristallstrukturen von Phasen im Al-reichen Bereich der Systeme Mo-Cu-Al, Re-Ni-Al und Mo-Ni-Al wurden bestimmt. Im W-Ni-Al-system, wurde eine neue Phase dokumentiert [(WNi2-x-y yAl8+x-z z, (x = 0.162, y = 0.015, z = 0.010)]. ReNi2Al8-x (x = 0.033), [MoNi2-xAl8+x (x = 0.166)] und (WNi2-x-y yAl8+x-z z, (x = 0.162, y = 0.015, z = 0.010) haben die gleiche Struktur die sich als eine Überstruktur vom Mo(CuxAl1-x)6Al4(x=0.416)-typ ableitet. DieVickers Härte (Hv) von Re-Ni-Al, Mo-Ni-Al, W-Ni-Al und Ni2Al3 wurde ebenfalls in dieser Arbeit evaluiert. Da Palladium in derselben Gruppe wie Nickel vorkommt, erwartet man sich eine Ähnlichkeit bezüglich der Phasenbeziehungen und der Kristallstrukturen. Aus diesem Grund wurde ein Teil des isothermen Bereichs des Al-reichen Bereichs des Mo-Pd-Al-systems bei 860° C studiert. Zwei ternäre Phasen (genannt t1 und t2) wurden entdeckt und über die Kristallstruktur und Mikrohärte der τ1-MoPd2-xAl8+x Phase wurde in dieser Arbeit berichtet. τ1-MoPd2-xAl8+x ist eine Überstruktur des Mo(CuxAl1-x)6Al4 Typs. Inspiriert von diesen strukturellen Zusammenhängen, wurde auch der Al-reiche Teil des Zr-Cu-Al-systems erforscht. Eine Einkristalluntersuchung von τ7-Zr(Cu1-xAlx)12, x = 0.514 trug dazu bei, den Homogenitätsbereich dieser Phase zu verstehen, die wegen des Cu/Al-Austausches mit gleichbleibendem Zr-gehalt als „line-compound“ auftritt. Die Al-reiche Phase τ9-ZrCu1-xAl4, x = 0.144 kristallisiert in einem neuen Strukturtyp und ist eine Überstruktur des fcc-Cu Typs und besteht aus der Kombination von drei Blöcken der Kupfereinheitszelle. Das Hinzufügen von Bor kann in Siliciden des Nb und Ta die Festigkeit und den Widerstand gegen Oxidation erhöhen. Aus diesem Grund wurde eine Röntgenstrukturanalyse am Einkristall vorgenommen um heraus zu finden, welchen Gitterplatz die Bor-atome in den Ta3Si- und Ta5Si3-Phasen bevorzugen. Weiters wurde die Gitterplatzpräferenz für zwei Phasen [Ta5(SiB)3 und Ta5Si3B1-x] mit Hilfe von Neutronenpulverstreuung (NPD) studiert. Für die Ta5Si3B1-x Phase wurde der Ti5Ga4 Strukturtyp ermittelt. Das Ta-V-Si-system wurde vollständig untersucht und ein kompletter isothermer Schnitt bei 1500° C und ein Teilschnitt bei 1200° C konnten bestimmt werden. Zwei ternäre Verbindungen τ1 und τ2 wurden bei diesen beiden Temperaturen gefunden die dem Mn5Si3 Typ und MgZn2 Type entsprechen. Zusätzlich konnte gezeigt werden, dass Si eine ternäre MgCu2-type Lavesphase bei dieser Temperatur stabilisiert die vom binären Ta-V-system durch Konnoden getrennt ist. Das konstruierte Phasendiagramm stimmt gut mit dem nach der CALPHAD-Methode berechneten thermodynamischen Modell überein. Ein isothermer Teilschnitt wurde im Ta-V-Ge-system bei 1500° C erstellt. Zusätzlich zu den Phasen, die auch im Ta-V-Ge-system [Strukturtyp τ1-Mn5Si3, Strukturtyp τ2-MgZn2 und Strukturtyp MgCu2] auftreten, wurden zwei ternäre Phasen (Strukturtyp τ3-Nb9Co4Ge und eine unbekannte Struktur τ4) gefunden. Die Struktur der Lavesphase vom MgZn2-typ wurde mittels Rietveld Verfeinerung der Röntgenpulveraufnahme und unter Verwendung eines Durchstrahlelektronenmikroskops (TEM) bestätigt. V11Ge8 (Cr11Ge8-typ) zeigt bei 1500 °C eine große Löslichkeit bis zu (TaxV1-x)11Ge8, x = 0.639. Der Mn-reiche Teil des Ti-Mn-systems wurde unter Einsatz von Röntgenstruktur- DTA- und EDX-analysen an Hand von Proben die im Lichtbogen geschmolzen und dann geglüht wurden neu untersucht. Die Kristallstrukturen von Ti6(Ti1-xMnx)6Mn25, x = 0.462 (TiMn~3) und Ti8(TixMn1-x)6Mn39, x = 0.187 (TiMn~4) konnten mittels Röntgendiffraktion am Einkristall aufgeklärt werden. Eine einphasige Probe von Ti8(TixMn1-x)6Mn39, x = 0.187 (TiMn~4) wurde für die Messung verschiedener physikalischer Eigenschaften hergestellt.Ti-based alloys have a wide range of applications. They are being used not only in turbine and automotive industry but also in aerospace applications. In additional to that, they are potential candidates for hydrogen storage materials. In many cases, they are used in combination with Al. Both Ti and Al have the advantage of lightweight and are valuable constituents of high strength alloys. Al based materials are widely used in industry as well as in home appliances. Si is a very important alloying partner and Si base alloys are promising materials for high temperature applications because of their high melting points and good resistance to oxidation. Detailed knowledge on phase equilibria and crystal structure is very important for the selection and design of high quality materials. The purpose of this research work was to provide the information on crystal structure and phase relations of Ti, Al and Si-based systems as well as to clarify the inconsistencies present in the literature. Although the Ti-Ni-Al system has been thoroughly studied in the past, several problems prevailed and have been clarified in this work using combined XRD and neutron powder diffraction as well as EPMA analyses. Two four-phase reactions of transition type have been defined. The crystal structure of the two compounds in the Al-rich region (τ5-TiNi2-xAl5, x = 0.48) and in the Ti-rich region [τ6-Ti2(Ti,Ni,Al)3] of the Ti-Ni-Al system has been solved from X–ray powder and single crystal combined with neutron powder diffraction. In addition to that, phase relations especially those related to the Ti-rich phase [τ6-Ti2(Ti,Ni,Al)3] are studied, clarified and reported in this study. The crystal structures of phases in the Al-rich corner in the systems Mo-Cu-Al, Re-Ni-Al and Mo-Ni-Al have been determined. In the W-Ni-Al system, the presence of a new phase is reported [(WNi2-x-y yAl8+x-z z, (x = 0.162, y = 0.015, z = 0.010)]. ReNi2Al8-x (x = 0.033), [MoNi2-xAl8+x (x = 0.166)] and (WNi2-x-y yAl8+x-z z, (x = 0.162, y = 0.015, z = 0.010) have the same structure which is a superstructure of the Mo(CuxAl1-x)6Al4 (x=0.416)-type. Vickers hardness (Hv) of Re-Ni-Al, Mo-Ni-Al, W-Ni-Al and Ni2Al3 has also been evaluated as part of this work. As Pd lies in the same group with Ni, one expects some similarity in phase relations as well as in crystal structure. So the partial isothermal section at 860 °C has been studied for the Al-rich part of the Mo-Pd-Al system. Two ternary phases (named t1 and t2) were found out of which, crystal structure and micro-hardness of the τ1-MoPd2-xAl8+x phase is measured. τ1-MoPd2-xAl8+x is a superstructure of the Mo(CuxAl1-x)6Al4 type. Inspired by these structural relations, the Al-rich part of the Zr-Cu-Al system was also studied. A single crystal study of τ7-Zr(Cu1-xAlx)12, x = 0.514 helped in understanding the homogeneity region of this phase, which appears as a line compound due to the Cu/Al exchange with constant Zr content. The Al-rich phase τ9-ZrCu1-xAl4, x = 0.144 crystallized in a novel structure type and is a superstructure of Cu appearing from the combination of three blocks of the Cu unit cell. Addition of boron can enhance the strength and oxidation resistance of Nb,Ta-based silicides. For this purpose, single crystal X-ray diffraction was used to find the atom site preference of B in Ta3Si and Ta5Si3 phases. Similarly, B site preference for two phases [Ta5(SiB)3 and Ta5Si3B1-x] was studied using Neutron Powder Diffraction (NPD). The Ta5Si3B1-x-phase was proven to adopt the Ti5Ga4 structure type. The Ta-V-Si system was thoroughly studied and a complete isothermal section at 1500 °C and a partial isothermal section at 1200 °C have been derived. Two ternary compounds τ1 and τ2 were found at these two temperatures with Mn5Si3 type and MgZn2 type, respectively. In addition to that, Si was found to stabilize a ternary MgCu2-type Laves phase at this temperature, which separates from the binary Ta-V system. Constructed phase diagram agrees well with the thermodynamic modelling based on CALPHAD approach. A partial isothermal section is reported in the Ta-V-Ge system at 1500 °C. In addition to the phases also seen in the Ta-V-Si system [τ1-Mn5Si3 structure type, τ2-MgZn2 structure type and MgCu2 structure type], two additional ternary phases (τ3-Nb9Co4Ge type structure and τ4-unknown structure) were found. MgZn2-type Laves phase was confirmed by Rietveld Refinement of X-ray Powder Diffraction and transmission electron microscopy (TEM). V11Ge8 (Cr11Ge8 type) shows a large solubility up to (TaxV1-x)11Ge8, x = 0.639 at 1500 °C. The Mn-rich part of the Ti-Mn system was reinvestigated by X-ray, DTA and EDX analyses on arc melted and annealed alloys. The crystal structure of Ti6(Ti1-xMnx)6Mn25, x = 0.462 (TiMn~3) and Ti8(TixMn1-x)6Mn39, x = 0.187 (TiMn~4) was solved from X-ray single crystal diffraction data. Single phase sample of Ti8(TixMn1-x)6Mn39, x = 0.187 (TiMn~4) was prepared for the measurement of different physical properties

Climatic Changes and Their Effect on Wildlife of District Dir Lower, Khyber Pakhtunkhwa, Pakistan

Climatic changes and their impact are increasingly evident in Pakistan, especially in the mountainous regions. Mountain ecosystems are considered to be sensitive indicators of global warming; even slight variations in temperature can lead to significant shifts in local climate, which can, in turn, drastically affect the natural environment, subsequently altering people’s lifestyle and wildlife habitats. The targeted area for the present research was Lower Dir District, Pakistan. The study gathered the required information from primary and secondary sources. Secondary data on temperature and precipitation were obtained from various sources, i.e., local CBO, including WWF Pakistan. Based on information gathered on climate change and wildlife, a detailed questionnaire was designed. Results showed that no regular pattern of the increase was found in temperature from 2010 to 2018; the same was noticed in the rainfall decrease pattern. Results also showed that the leading causes behind climatic changes are an increase in greenhouse gases due to pollution by industries, vehicles, crushing plants, deforestation, and some natural phenomena such as floods. The study showed that more than 80% of the respondents agreed that climatic effects have a significant impact on wildlife, i.e., the existence of wildlife falls in danger due to climatic changes as it may lead to habitat change, making it difficult for the survival and adaptation of the wildlife. Hence, in consequence, it leads to migration, low growth rate, an increase in morbidity and mortality rate, and finally leading to the extinction of the species or population. It is concluded from the study that people are severely noticing the climatic change and its leading causes are greenhouse gases and deforestation. To control climatic changes and wildlife extinction, we need an appropriate policy for forest conservation, wildlife conservation, prevent hunting, industrial pollution control, vehicle pollution control, increase in plantation, awareness of policy for the control of climatic changes, etc

Partnerships to improve access and quality of public transport - a case report: Faisalabad, Pakistan

This book presents findings from project R7786 Partnerships to improve access and quality of urban public transport for the urban poor carried out by the authors as part of the Knowledge and Research (KaR) programme of the Infrastructure and Urban Development Department, Department for International Development (DFID) of the British Government. The purpose of the project was to identify, explore, and document critical issues in the provision of transport services for and in low-income settlements in developing countries. The identified issues can be used at policy and operational levels to provide better transport services to low-income communities in urban areas. In the research methodology, a sustainable livelihoods framework was used to set the research framework. Faisalabad has 1,977,246 residents at the time of the most recent census in 1998, and it is likely that the population is now well in excess of 2 million. The traffic growth rate was 4.25 per cent in 1991, and that growth rate is likely to be maintained. Public transport availability varies strongly according to the nature of the community, but has not grown at the same rate as the work force. 60 per cent of the city's population live in 'colonies', which are planned developments recognised and accepted by the council. The remainder live in 'Katchi abadies' (houses developed in an unplanned manner and illegally occupied by squatters) or slums consisting of poor people who have moved to the edge of the city in the hope of finding work or education

Socio-economic Status of Transferred and Non-transferred Urban Slums: A Case Study from Faisalabad

The rapid urbanisation has become a burning challenge across the developing countries of the world for the last four decades. The population pressure on the cities has caused many problems like environmental pollution, sanitation, education, health, traffic level and housing etc. In this context, housing is one of the most important issues related to urbanisation. Slums are reflected as the carbuncle in cities and looked extemporaneously and arbitrarily [Shafqaat, et al. (2013). The share of world urban population was 32 percent in 1950, it rose up to 39 percent in 1980 and 48 percent in 2000, which reflects that 3 out of 10 people were living in cities in 1950. In 2011, about half of the world population was living in the big cities and at the end of the third decade of this century; that make up the formation as 6 out of 10 people [World Bank (1999)]. Pakistan‘s town populace is fixed to become identical to its rural population in the year 2030. This needs for an effective urban planning instrument to confirm universal distribution of simple municipal amenities, regulator of the spread of slums, reducing of effluence and the control of crime and political might [Khan, et al. (2012)

Factors determining capital structure of Pakistani non-financial firms.

This study is undertaken to discover the factors determining the capital structure decision of non-financial Pakistani firms. The capital structure irrelevance theory, trade off theory and pecking order theory stipulates different factors affecting a firm’s optimal debt/equity choice. However, the literature is still inconclusive about which factors and theories best defines the ideal capital structure mix. Thus, making it an unanswered, open empirical question, that, needs to be explored especially for sectors not previously studied. The effect of firm’s profitability, liquidity, size, tangibility and non-debt tax shield on capital structure decision of ten non-financial firms operating at Pakistan Stock Exchange is investigated for a period of ten years i-e from 2005-2014. By using fixed effects panel estimation method it is found that leverage ratio is inversely affected by profitability and current ratio of a firm. While, firm size, tangibility and non-debt tax shield positively effects leverage ratio. The influence of profitability is weakly significant whereas that of liquidity, size, tangibility and non-debt tax shield are strongly significant. The study also shows that results for profitability and liquidity are in accordance with the Pecking Order Theory and the result for size; tangibility and non-debt tax shield are in line with the Trade-Off Theory

Opinion mining summarization and automation process a survey

In this modern age, the internet is a powerful source of information. Roughly, one-third of the world population spends a significant amount of their time and money on surfing the internet. In every field of life, people are gaining vast information from it such as learning, amusement, communication, shopping, etc. For this purpose, users tend to exploit websites and provide their remarks or views on any product, service, event, etc. based on their experience that might be useful for other users. In this manner, a huge amount of feedback in the form of textual data is composed of those webs, and this data can be explored, evaluated and controlled for the decision-making process. Opinion Mining (OM) is a type of Natural Language Processing (NLP) and extraction of the theme or idea from the user's opinions in the form of positive, negative and neutral comments. Therefore, researchers try to present information in the form of a summary that would be useful for different users. Hence, the research community has generated automatic summaries from the 1950s until now, and these automation processes are divided into two categories, which is abstractive and extractive methods. This paper presents an overview of the useful methods in OM and explains the idea about OM regarding summarization and its automation process

Measuring the BDARX architecture by agent oriented system a case study

Distributed systems are progressively designed as multi-agent systems that are helpful in designing high strength complex industrial software. Recently, distributed systems cooperative applications are openly access, dynamic and large scales. Nowadays, it hardly seems necessary to emphasis on the potential of decentralized software solutions. This is because the main benefit lies in the distributed nature of information, resources and action. On the other hand, the progression in multi agent systems creates new challenges to the traditional methodologies of fault-tolerance that typically relies on centralized and offline solution. Research on multi-agent systems had gained attention for designing software that operates in distributed and open environments, such as the Internet. DARX (Dynamic Agent Replication eXtension) is one of the architecture which aimed at building reliable software that would prove to be both flexible and scalable and also aimed to provide adaptive fault tolerance by using dynamic replication methodologies. Therefore, the enhancement of DARX known as BDARX can provide dynamic solution of byzantine faults for the agent based systems that embedded DARX. The BDARX architecture improves the fault tolerance ability of multi-agent systems in long run and strengthens the software to be more robust against such arbitrary faults. The BDARX provide the solution for the Byzantine fault tolerance in DARX by making replicas on the both sides of communication agents by using BFT protocol for agent systems instead of making replicas only on server end and assuming client as failure free. This paper shows that the dynamic behaviour of agents avoid us from making discrimination between server and client replicas

Lipid Profiles and Its Association with Pre-Eclampsia and Eclampsia in Nulliparous Pregnant Women

Objectives: To access the lipid profiles and its association with pre-eclampsia and eclampsia in nulliparous pregnant women. Material and Methods: This cross-sectional study was performed on 234 nulliparous pregnant women with gestation period of  > 20 weeks and aged 15-45 years, from March to October 2014, in Institute of Basic Medical Sciences (IBMS), Khyber Medical University (KMU), Peshawar, Pakistan with cooperation from gynecology and obstetrics departments of three tertiary-care hospitals of Peshawar & Khyber Medical College, Peshawar,  Khyber Pakhtunkhwa (KP), Pakistan. Subjects were assigned to three groups i.e., group A, group B and group C. For performing biochemical assays and lipid profiling, through ELISA, blood samples were collected from already subjects both with the disease and the controls. Results: Both subjects having pre-eclampsia and eclampsia showed significant elevated levels (p < 0.001) for low density lipoproteins cholesterols (LDL-c), high density lipoprotein cholesterol (HDL-c), total cholesterol (TC)/HDL-c and LDL-c/HDL-c ratio. But TC of pre-eclampsia subjects were found significantly elevated (p < 0.001) in relation to controls. LDL-c/HDL-c and TC/HDL-c also revealed an elevated significant change (p < 0.001) both for pre-eclamptic and eclamptic subjects. On the other hand, only TG/HDL-c in pre-eclamptic patients was found significantly higher (p<0.004) when compared to control group.  Conclusion: Serum lipid levels were observed higher in pre-eclampsia and eclampsia patients hence an early assessment is necessary to prevent complications in such patients

Synthesis, characterization and biological activities of hydrazone schiff base and its novel metals complexes

Recently, researchers are focusing on the synthesis of Schiff base complexes due to their promising biological activities and frequent use in the pharmaceuticals. In the present study we synthesized Schiff base of salicyldehyde and 2, 4-dinitrophenylhydrazine by modified method and its novel metal complexes with Cu (II), Zn (II), Co (II), Ni (II), Mn (II), V (II) and AU (IIII). For spectroscopic studies and characterization, UV-Vis and FT-IR spectroscopy were used. The Schiff base and its metals complexes were tested for antimicrobial, cytotoxic and antioxidant activities. Significant results are showed by the all synthesized complexes