RIEWALD" and solid solution indented with microindenter. Information o - PDF document

RIEWALD" and solid solution indented with microindenter. Information on mechan- and by Manganous selenide exhibits primary and in contrast to the Behavior and Hardness The zone-refined grains large used in single placed in a graphite fused silica. This was placed inside silica tube coil to produce single crystals large for study. individual components were crushed mesh, mixed in the desired proportions, and then handled were cleaved large grains and annealed They were oriented by Laue back-reflection technique and cut veal the orientations were to within Samples were mounted in solder for and mechanically micrographic techniques. Care was polishing to remove chemically possible dis- surface layers oxalic acid. sequent Laue photographs revealed significant residual deformation in the were then indented with or a denter was made parallel to index crystallo- planes tested. lines were observed directly around indentations in lines on the several crystal surfaces, the slip occurred be deduced. was also studied by observing hardness variations orientation and sample inducing cleavage planes and by noting in crushed any fracturing around indentations was related to slip interactions. Deformation: The slip that the glide planes The slip directions were assumed close-packed direc- these planes, giving a Burgers plane (Fig. directions, whereas whereas and ᄠdirections (only those since they differential thermal to create cause (111) and cross found in fcc metals and found in This tendency in MnSe reflected in other material (higher), and anion polarizability that the covalent-metallic and selenide shows primary and planes, respectively. This behavior indentation tended to produce near the corners in regions perpendicular intersecting slip lines also concentrated. that the (100) is the a slip dislocation interaction mechanism cleavage crack. Vickers diamond pyramid relative to the shape were shaped impressions Vickers impressions piled-up regions in sinking-in in in which indenter diagonals this feature penetrating the surface causes crystallographic plastic the form the symmetry crystal. The determines the shape this deformation seen where extensive pileup The concentrations slip lines and surface crystallographic directions however. They the primary glide mechanism. directions around occurred predominantly fracture was the (110) frac- Interference photomicrographs around indenter diagonals diagonals + a/2[101] -+ a/2[110] (1) resulting in against this piled-up dislocations other parallel glide planes, reducing pileup like simpler way adjacent (101) planes tends to 110) plane (100) fracture in MnSe may be each (111) which would plane. It to postulate interactions form- dislocations leading dislocation pileup and, the absence absence + a/a[ilo] -+ ~/Z[OZO] = a[010] a/2[110] + a/2[011] -+ a/a[loi] Slip Behavior and Hardness Indentatiom in MnSe and MnSe-MnS (2) (3 ) 373 Both of the resulting dislocations are of the edge variety and and intersection of two adjacent (111) The first and the quite intimately related to by barriers less and Plastic Deformation: secondary mechanism in MnSe, Vickers indentations. at.% substitution selenide, however, traces due became more Vickers indentation to (110) those in mechanisms were operative for compositions studied. modes associated indentation also change gradually primarily (100) example, Fig. shows a (100) crack Pyramid Hardness: 4 shows diamond pyramid (Vickers) hardness with com- temperature, and mechanisms other than those discussed were different amounts glide took variation by were the Manganous selenide softer than manganous 145 kg/mm2 its hardness sensitive to a line between accompanies the also produces a positive deviation. becomes just to activate appreci- the secondary mechanism It was not possible obtain reliable Vickers hardness room temperature, and for samples which occurs,4 mentioned previously. The variation materials is well-known phenomenon. the hardness the particular slip systems to accommodate the indenter. Because 48 54 119 142 142 140 than for hardness results for these that, for is softer is parallel to is true soft directions for becomes possible glide mechanism indenter orientations. These results that similar selenide but a marked increase and resulted in toward higher temperature, the mechanism contributes the overall deformation and, consequently, shifts right. Similarly, temperatures, the be expected This effect was observed. manganous selenide (MnSe) slip mechanisms, respectively. This secondary (110) cleavage also evident. This ment with indentations in around Vickers indentations on MnSe and a in others. The pileup directions, indenter orientation, produce impressions square. This to the tion on material prefers resulting in four piled-up hills along piled-up regions preferential plastic the continuous solid solution system slip mechanism changes common in in DIR. -- 0-- [IlO] OIR. 0 10 20 30 40 50 60 70 80 90 100 MOLE PERCENT MnS 40 0 10 20 30 40 50 60 70 80 90 100 MOLE PERCENT MnS Fig. 5. Knoop hardness indenter orientations solid solutions temperature and selenide ions sulfide ions in solution-hardening deviation from simple two end-member values. much softer pyramid hardness the same and (111) in the system. The to decreasing temperature than the appreciable amount anisotropy behavior specimens. Manganese softest when it is reverse is The reversal hard and gradual change with composi- authors thank Selenium-Tellurium Development original dis- Riewald acknowledges financial sup- port he Kagle, Crystallographic Structures. Dover Publications, in Some Manganous Manganous 922-25 (1939). ‘H. P. Rooksby and N. C. Tombs, “Changes of Crystal Structure in Antiferromagnetic Compounds,” Nature, 167 [4?44] 364 Makovetskii, “Neutron Diffraction MnSe,” Dokl. Akad. Akad. 542-45 (1966). J. M. Mehta, P. G. Riewald, and L. H. Van Vlack, Vlack, 164 (1967). R. Kiessling, B. Hassler, and C. Westman, “Selenide- Sulfide Inclusions (Mn, Me) Me) 531-34 (1967). J. J. Gilman; pp. 146-99 in Progress in Ceramic Inc., New NaCI-Structure,” Actu Actu 459-62 (1567). ‘A. S. Keh, “Dislocations in Indented Magnesium Magnesium 1538-45 1960). Chao, L. L. H. H. 386-98 (1964). J. W. Moore, “Structure and Properties of Oriented Com- pound Eutectics”; Ph.D. Thesis, University of Michigan, 1965; Univ. Microfilms (Ann Arbor, Mich.), Mich.), 7243-44 (1966). in Micro-Indentation Micro-Indentation 49-100 (1959). Mobility of Cation Vacancies in the i, Solid Solution KCl-RbCl J. B. HQLT,* H. G. SQCKEL, and H.SCHMALZRIED Institut fur Theoretische Huttenkunde, Technische CIausthal, ClausthaI-Zellerfeld, the way the jump solid solution provide experimental for analysis, these measurements this system The relation defects predominate, by the two compounds combined in that the cation environment surrounding vacancy can least three cases the three with composition represents the been considered dilute metallic under restricting assumptions, depend on composition. the measured should reflect change in cations around given vacancy, in the varied from pure to pure solid solution, to have similar physical characteristics. with composition to form pure and Schmalzried“ in Received November copy received Supported in time this batical leave Lawrence Radiation Laboratory, Humboldt Founda- tion in