Exploiting superior tensile properties of a novel network-structure AlA206 matrix composite by hybridizing micron-sized Al3Ti with Al2O3 nano particulates

In this study, semi-solid stir casting and ball milling processes are combined into an integrated composite fabrication process. Two different architectures were utilized to incorporate reinforcing particle into semi-solid alloy i.e., (i) ball milling of K2TiF6 and aluminum powder for 5h and subsequently with nano-alumina particles (Al2O3np) for 1h and (ii) ball milling of K2TiF6, Al2O3np and aluminum powder for 2h. Accordingly, the milled powders were incorporated into molten AlA206 alloy using a non-contact ultrasonic vibration method. The effect of milling procedure on microstructural evolution and tensile properties were then explored. Two different microstructures were characterized including well-distributed Al2O3np and Al3Ti particles (Al3Tip) and a network-structure containing Al3Tip+Al2O3np. This unique architecture of network-structure brought about increment in tensile properties compared to well-distributed reinforcement particles, ascribed to the strewing of Al3Tip+Al2O3np around matrix grain boundaries, act as a three-dimension skeletal structure with high local volume fraction of Al3Tip+Al2O3np

Effect of Concept Map on the Academic Achievement of the High school Students in Physics

In this regard, the conceptual map has been presented for improving the common teaching programs. In present study the effect of conceptual map on academic achievement of high school students of girl and boy in physics lesson has been investigated. This research involved two semi-experimental research and case study sections. The semi-experimental research aimed to determine the effectiveness of proposing conceptual map and presentation and making of conceptual map in academic achievement of the learners in physics. This case study was conducted in order to study the effect of meaningfulness of the conceptual map for investigation of the causes for survey on the teachers and professors experiences in effectiveness of the application of the conceptual map in learning- teaching process. In the semi-experimental section, pre-test and post-test were used and six classes of secondary school were selected by purposeful sampling method (two conceptual map classes, two proposing and making conceptual map and two control classes). In the control groups, the learners learned the mentioned lessons by common method. In the presentation and making group (combined group), curriculums were presented in the conceptual form and also the students prepared the conceptual maps of the taught subjects. In the experimental representation group, the subjects were presented only in the conceptual map form. The effect of this combination on the learners’ academic achievement was measured by academic achievement test. The results of Covariance analysis showed that the scour of students in combine and teacher made tested groups in post-tested were more than the control group (p˂0/001). So, using of the concept map led to increase of academic achievement in students. The other results show that none of the female and male groups had privilege to each other. Also, for fulfilling the second goal of the research, the opinions and experiences of nine teachers and professors on the effectiveness of the application of the conceptual map in learning-teaching process were investigated. The sampling of the teachers and professors was done as purposeful and the data were selected as semi structured interview. The findings of the teachers and professors experiences on the effectiveness of the application of the conceptual map were summarized under three main categories of holistic view, self-regulatory learning and growth of thought and several secondary contents